#include <db_cxx.h>

DbEnv::set_lk_partitions(u_int32_t partitions); 

Set the number of lock table partitions in the Berkeley DB environment. The default value is 10 times the number of CPUs on the system if there is more than one CPU. Increasing the number of partitions can provide for greater throughput on a system with multiple CPUs and more than one thread contending for the lock manager. On single processor systems more than one partition may increase the overhead of the lock manager. Systems often report threading contexts as CPUs. If your system does this, set the number of partitions to 1 to get optimal performance.

The database environment's number of partitions may also be configured using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_lk_partitions", one or more whitespace characters, and the number of partitions. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

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

The DbEnv::set_lk_partitions() 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_lk_partitions() will be ignored.

The DbEnv::set_lk_partitions() 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 partitions parameter is the number of partitions to be configured in the Berkeley DB environment.


The DbEnv::set_lk_partitions() method may fail and throw a DbException exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:


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


DbEnv, DbLock

See Also

Locking Subsystem and Related Methods