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<title>Berkeley DB: DbTxn::commit</title>
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<h1>DbTxn::commit</h1>
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#include <db_cxx.h>
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DbTxn::commit(u_int32_t flags);
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<p>The DbTxn::commit method ends the transaction.
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<p>In the case of nested transactions, if the transaction is a parent
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transaction, committing the parent transaction causes all unresolved
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children of the parent to be committed. In the case of nested
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transactions, if the transaction is a child transaction, its locks are
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not released, but are acquired by its parent. Although the commit of the
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child transaction will succeed, the actual resolution of the child
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transaction is postponed until the parent transaction is committed or
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aborted; that is, if its parent transaction commits, it will be
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committed; and if its parent transaction aborts, it will be aborted.
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<p>The <b>flags</b> value must be set to 0 or
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one of the following values:
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<p><dt><a name="DB_TXN_NOSYNC">DB_TXN_NOSYNC</a><dd>Do not synchronously flush the log. This means the transaction will
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exhibit the ACI (atomicity, consistency, and isolation) properties, but
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not D (durability); that is, database integrity will be maintained, but
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it is possible that this transaction may be undone during recovery.
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<p>This behavior may be set for a Berkeley DB environment using the
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<a href="../api_cxx/env_set_flags.html">DbEnv::set_flags</a> interface or for a single transaction using the
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<a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a> interface. Any value specified in this interface
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overrides both of those settings.
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<p><dt><a name="DB_TXN_SYNC">DB_TXN_SYNC</a><dd>Synchronously flush the log. This means the transaction will exhibit
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all of the ACID (atomicity, consistency, isolation, and durability)
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<p>This behavior is the default for Berkeley DB environments unless the
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<a href="../api_cxx/env_set_flags.html#DB_TXN_NOSYNC">DB_TXN_NOSYNC</a> flag was specified to the <a href="../api_cxx/env_set_flags.html">DbEnv::set_flags</a>
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interface. This behavior may also be set for a single transaction using
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the <a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a> interface. Any value specified in this interface
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overrides both of those settings.
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<p>All cursors opened within the transaction must be closed before the
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transaction is committed.
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<p>After DbTxn::commit has been called, regardless of its return, the
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<a href="../api_cxx/txn_class.html">DbTxn</a> handle may not be accessed again. If DbTxn::commit
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encounters an error, the transaction and all child transactions of the
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transaction are aborted.
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<p>The DbTxn::commit method either returns a non-zero error value or throws an exception that
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encapsulates a non-zero error value on failure, and returns 0 on success.
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<p>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.
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If a catastrophic error has occurred, the DbTxn::commit method may fail and
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either return <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a> or throw a
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<a href="../api_cxx/runrec_class.html">DbRunRecoveryException</a>,
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in which case all subsequent Berkeley DB calls will fail in the same way.
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<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/txn_class.html">DbTxn</a>
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<a href="../api_cxx/txn_list.html">Transaction Subsystem and Related Methods</a>
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