<!--$Id: sync.so,v 10.15 2000/12/18 21:05:14 bostic Exp $--><!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--><!--All rights reserved.--><html><head><title>Berkeley DB Reference Guide: Flushing the database cache</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>Access Methods</dl></h3></td><tdwidth="1%"><ahref="../../ref/am/delete.html"><imgsrc="../../images/prev.gif"alt="Prev"></a><ahref="../../ref/toc.html"><imgsrc="../../images/ref.gif"alt="Ref"></a><ahref="../../ref/am/stat.html"><imgsrc="../../images/next.gif"alt="Next"></a></td></tr></table><p><h1align=center>Flushing the database cache</h1><p>The <ahref="../../api_c/db_sync.html">DB->sync</a> function is the standard interface for flushing all modifiedrecords from the database cache to disk.<p><b>It is important to understand that flushing cached informationto disk only minimizes the window of opportunity for corrupted data, itdoes not eliminate the possibility.</b><p>While unlikely, it is possible for database corruption to happen if asystem or application crash occurs while writing data to the database. Toensure that database corruption never occurs, applications must either:<ultype=disc><li>Use transactions and logging with automatic recovery.<li>Use logging and application-specific recovery.<li>Edit a copy of the database, and, once all applicationsusing the database have successfully called <ahref="../../api_c/db_close.html">DB->close</a>, usesystem operations (e.g., the POSIX rename system call) to atomicallyreplace the original database with the updated copy.</ul><table><tr><td><br></td><tdwidth="1%"><ahref="../../ref/am/delete.html"><imgsrc="../../images/prev.gif"alt="Prev"></a><ahref="../../ref/toc.html"><imgsrc="../../images/ref.gif"alt="Ref"></a><ahref="../../ref/am/stat.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>