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<title>Berkeley DB Reference Guide: Configuring transactions</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Transaction Subsystem</dl></h3></td>
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<h1 align=center>Configuring transactions</h1>
<p>There is only a single parameter used in configuring transactions, the
<a href="../../api_c/env_open.html#DB_TXN_NOSYNC">DB_TXN_NOSYNC</a> flag. Setting the <a href="../../api_c/env_open.html#DB_TXN_NOSYNC">DB_TXN_NOSYNC</a> flag to
<a href="../../api_c/env_set_flags.html">DBENV->set_flags</a> when opening a transaction region changes the
behavior of transactions not to synchronously flush the log during
transaction commit.
<p>This change will significantly increase application transactional
throughput. However, it means that while transactions will continue to
exhibit the ACI (atomicity, consistency and isolation) properties, they
will not have D (durability). Database integrity will be maintained but
it is possible that some number of the most recently committed
transactions may be undone during recovery instead of being redone.
<p>The application may also limit the number of simultaneous outstanding
transactions supported by the environment by calling the
<a href="../../api_c/env_set_tx_max.html">DBENV->set_tx_max</a> function. When this number is met, additional calls to
<a href="../../api_c/txn_begin.html">txn_begin</a> will fail until some active transactions complete.
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