# DB_ENV->set_lk_detect

`

###

    #include <db.h>

    int
    DB_ENV->set_lk_detect(DB_ENV *dbenv, u_int32_t detect);

# Description

Set if the deadlock detector is to be run whenever a lock conflict occurs, and specify which transaction should be aborted in the case of a deadlock. The specified value must be one of the following list:

DB_LOCK_DEFAULT
  Use the default policy as specified by db_deadlock.
DB_LOCK_MAXLOCKS
  Abort the transaction with the greatest number of locks.
DB_LOCK_MINLOCKS
  Abort the transaction with the fewest locks.
DB_LOCK_MINWRITE
  Abort the transaction with the fewest write locks.
DB_LOCK_OLDEST
  Abort the oldest transaction.
DB_LOCK_RANDOM
  Abort a random transaction involved in the deadlock.
DB_LOCK_YOUNGEST
  Abort the youngest transaction.

The DB_ENV->set_lk_detect interface may be used only to configure Berkeley DB before the DB_ENV->open interface is called.

The DB_ENV->set_lk_detect function returns a non-zero error value on failure and 0 on success.

The database environment's deadlock detector configuration 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_lk_detect", one or more whitespace characters, and the interface detect argument as a string; for example, "set_lk_detect DB_LOCK_OLDEST". Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

# Errors

The DB_ENV->set_lk_detect function may fail and return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

  Called after DB_ENV->open was called.

The DB_ENV->set_lk_detect function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB_ENV->set_lk_detect function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# See Also

DB_ENV->set_lk_conflicts, DB_ENV->set_lk_detect, DB_ENV->set_lk_max, DB_ENV->set_lk_max_lockers, DB_ENV->set_lk_max_locks, DB_ENV->set_lk_max_objects, lock_detect, lock_get, lock_id, lock_put, lock_stat, and lock_vec.`

Copyright Sleepycat Software