Set the maximum number of active transactions that are supported by the
environment. This value bounds the size of backing shared memory regions.
Note that child transactions must be counted as active until their
ultimate parent commits or aborts.
When there are more than the specified number of concurrent transactions,
calls to DbEnv::txn_begin will fail (until some active transactions
complete). If no value is specified, a default value of 20 is used.
The DbEnv::set_tx_max method configures a database environment, not only operations
performed using the specified DbEnv handle.
The DbEnv::set_tx_max 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_tx_max
will be ignored.
The DbEnv::set_tx_max 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 active transactions 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_tx_max", one or more whitespace characters,
and the number of transactions. 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_tx_max method may fail and throw an exception or return a non-zero error for the following conditions:
- An invalid flag value or parameter was specified.
Called after DbEnv::open was called.
The DbEnv::set_tx_max 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_tx_max method may fail and
either return DB_RUNRECOVERY or throw a
in which case all subsequent Berkeley DB calls will fail in the same way.
Transaction Subsystem and Related Methods
Copyright Sleepycat Software