Berkeley DB: DbEnv::set_lk_max_lockers
Description: 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_lk_max_lockers |

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    #include <db_cxx.h>

    int
    DbEnv::set_lk_max_lockers(u_int32_t max);

# Description

Set the maximum number of simultaneous locking entities supported by the Berkeley DB lock subsystem. This value is used by DbEnv::open to estimate how much space to allocate for various lock-table data structures. The default value is 1000 lockers. For specific information on configuring the size of the lock subsystem, see Configuring locking: sizing the system.

The DbEnv::set_lk_max_lockers method configures a database environment, not only operations performed using the specified DbEnv handle.

The DbEnv::set_lk_max_lockers interface may not be called after the DbEnv::open interface is called. If the database environment already exists when DbEnv::open is called, the information specified to DbEnv::set_lk_max_lockers will be ignored.

The DbEnv::set_lk_max_lockers 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.

The database environment's maximum number of lockers 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_max_lockers", one or more whitespace characters, and the number of lockers. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

# Errors

The DbEnv::set_lk_max_lockers method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

  Called after DbEnv::open was called.

The DbEnv::set_lk_max_lockers method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the DbEnv::set_lk_max_lockers method may fail and either return DB_RUNRECOVERY or throw a DbRunRecoveryException, in which case all subsequent Berkeley DB calls will fail in the same way.

# Class

DbEnv, DbLock

# See Also

Locking Subsystem and Related Methods`

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