# Berkeley DB: DbTxn::commit
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++

# DbTxn::commit

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    #include <db_cxx.h>

    int
    DbTxn::commit(u_int32_t flags);

# Description

The DbTxn::commit method ends the transaction.

In the case of nested transactions, if the transaction is a parent transaction, committing the parent transaction causes all unresolved children of the parent to be committed. In the case of nested transactions, if the transaction is a child transaction, its locks are not released, but are acquired by its parent. Although the commit of the child transaction will succeed, the actual resolution of the child transaction is postponed until the parent transaction is committed or aborted; that is, if its parent transaction commits, it will be committed; and if its parent transaction aborts, it will be aborted.

The flags value must be set to 0 or one of the following values:

DB_TXN_NOSYNC
  Do not synchronously flush the log. This means the transaction will exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but it is possible that this transaction may be undone during recovery.

  This behavior may be set for a Berkeley DB environment using the DbEnv::set_flags interface or for a single transaction using the DbEnv::txn_begin interface. Any value specified in this interface overrides both of those settings.

DB_TXN_SYNC
  Synchronously flush the log. This means the transaction will exhibit all of the ACID (atomicity, consistency, isolation, and durability) properties.

  This behavior is the default for Berkeley DB environments unless the DB_TXN_NOSYNC flag was specified to the DbEnv::set_flags interface. This behavior may also be set for a single transaction using the DbEnv::txn_begin interface. Any value specified in this interface overrides both of those settings.

All cursors opened within the transaction must be closed before the transaction is committed.

After DbTxn::commit has been called, regardless of its return, the DbTxn handle may not be accessed again. If DbTxn::commit encounters an error, the transaction and all child transactions of the transaction are aborted.

The DbTxn::commit 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.

# Errors

The DbTxn::commit 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 DbTxn::commit 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, DbTxn

# See Also

Transaction Subsystem and Related Methods`

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