# 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. 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 DB_ENV->set_flags interface or for a single transaction using the 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 DB_ENV->set_flags interface. This behavior may also be set for a single transaction using the 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 txn_commit has been called, regardless of its return, 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

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

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