<!--$Id: config.so,v 10.14 2000/10/03 17:17:36 bostic Exp $--><!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--><!--All rights reserved.--><html><head><title>Berkeley DB Reference Guide: Configuring transactions</title><metaname="description"content="Berkeley DB: An embedded database programmatic toolkit."><metaname="keywords"content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"></head><bodybgcolor=white><aname="2"><!--meow--></a><table><trvalign=top><td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Transaction Subsystem</dl></h3></td><tdwidth="1%"><ahref="../../ref/txn/limits.html"><imgsrc="../../images/prev.gif"alt="Prev"></a><ahref="../../ref/toc.html"><imgsrc="../../images/ref.gif"alt="Ref"></a><ahref="../../ref/txn/other.html"><imgsrc="../../images/next.gif"alt="Next"></a></td></tr></table><p><h1align=center>Configuring transactions</h1><p>There is only a single parameter used in configuring transactions, the<ahref="../../api_c/env_open.html#DB_TXN_NOSYNC">DB_TXN_NOSYNC</a> flag. Setting the <ahref="../../api_c/env_open.html#DB_TXN_NOSYNC">DB_TXN_NOSYNC</a> flag to<ahref="../../api_c/env_set_flags.html">DBENV->set_flags</a> when opening a transaction region changes thebehavior of transactions not to synchronously flush the log duringtransaction commit.<p>This change will significantly increase application transactionalthroughput. However, it means that while transactions will continue toexhibit the ACI (atomicity, consistency and isolation) properties, theywill not have D (durability). Database integrity will be maintained butit is possible that some number of the most recently committedtransactions may be undone during recovery instead of being redone.<p>The application may also limit the number of simultaneous outstandingtransactions supported by the environment by calling the<ahref="../../api_c/env_set_tx_max.html">DBENV->set_tx_max</a> function. When this number is met, additional calls to<ahref="../../api_c/txn_begin.html">txn_begin</a> will fail until some active transactions complete.<table><tr><td><br></td><tdwidth="1%"><ahref="../../ref/txn/limits.html"><imgsrc="../../images/prev.gif"alt="Prev"></a><ahref="../../ref/toc.html"><imgsrc="../../images/ref.gif"alt="Ref"></a><ahref="../../ref/txn/other.html"><imgsrc="../../images/next.gif"alt="Next"></a></td></tr></table><p><fontsize=1><ahref="http://www.sleepycat.com">Copyright Sleepycat Software</a></font></body></html>