# txn_commit

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    #include <db.h>

    int
    txn_commit(DB_TXN *tid, u_int32_t flags);

# Description

The txn_commit function 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. While 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, i.e., if its parent transaction commits, it will be committed, and if its parent transaction aborts, it will be aborted.

The flags parameter 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), i.e., database integrity will be maintained but it is possible that this transaction may be undone during recovery instead of being redone.

  This behavior may be set for an entire Berkeley DB environment as part of the DBENV->set_flags interface.

DB_TXN_SYNC
  Synchronously flush the log. This means the transaction will exhibit all of the ACID (atomicity, consistency and 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 or txn_begin interfaces.

Once the txn_commit function returns, the DB_TXN handle may not be accessed again. If txn_commit encounters an error, the transaction and all child transactions of the transaction are aborted.

The txn_commit function returns a non-zero error value on failure and 0 on success.

# Errors

The txn_commit 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 txn_commit function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# See Also

DBENV->set_tx_max, DBENV->set_tx_recover, DBENV->set_tx_timestamp, txn_abort, txn_begin, txn_checkpoint, txn_commit, txn_id, txn_prepare and txn_stat.`

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