# Berkeley DB: DbEnv::set_data_dir
Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++

### DbEnv::set_data_dir

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    #include <db_cxx.h>

    int
    DbEnv::set_data_dir(const char *dir);

    int
    DbEnv::get_data_dirs(const char ***dirpp);

### Description: DbEnv::set_data_dir

Set the path of a directory to be used as the location of the access method database files. Paths specified to the Db::open function will be searched relative to this path. Paths set using this method are additive, and specifying more than one will result in each specified directory being searched for database files. If any directories are specified, created database files will always be created in the first path specified.

If no database directories are specified, database files can exist only in the environment home directory. See Berkeley DB File Naming for more information.

For the greatest degree of recoverability from system or application failure, database files and log files should be located on separate physical devices.

The database environment's data directories may also be set using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_data_dir", one or more whitespace characters, and the directory name.

The DbEnv::set_data_dir method configures operations performed using the specified DbEnv handle, not all operations performed on the underlying database environment.

The DbEnv::set_data_dir method may not be called after the DbEnv::open method is called. If the database environment already exists when DbEnv::open is called, the information specified to DbEnv::set_data_dir must be consistent with the existing environment or corruption can occur.

The DbEnv::set_data_dir method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

### Parameters

dir
  The dir parameter is a directory to be used as a location for database files.

### Errors

The DbEnv::set_data_dir method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

EINVAL
  If the method was called after DbEnv::open was called; or if an invalid flag value or parameter was specified.

### Description: DbEnv::get_data_dirs

The DbEnv::get_data_dirs method returns the NULL-terminated array of directories.

The DbEnv::get_data_dirs method may be called at any time during the life of the application.

The DbEnv::get_data_dirs method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

### Parameters

dirpp
  The DbEnv::get_data_dirs method returns a reference to the NULL-terminated array of directories in dirpp.

### Class

DbEnv

### See Also

Database Environments and Related Methods`

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