<!--$Id: sync.so,v 10.18 2003/10/18 19:15:53 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB Reference Guide: Flushing the database cache</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <a name="2"><!--meow--></a> <table width="100%"><tr valign=top> <td><b><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></b></td> <td align=right><a href="../am/verify.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../am/close.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p align=center><b>Flushing the database cache</b></p> <p>The <a href="../../api_c/db_sync.html">DB->sync</a> method flushes all modified records from the database cache to disk.</p> <p><b>It is important to understand that flushing cached information to disk only minimizes the window of opportunity for corrupted data, it does not eliminate the possibility.</b></p> <p>While unlikely, it is possible for database corruption to happen if a system or application crash occurs while writing data to the database. To ensure that database corruption never occurs, applications must either:</p> <p><ul type=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 applications using the database have successfully called <a href="../../api_c/db_close.html">DB->close</a>, use system operations (for example, the POSIX rename system call) to atomically replace the original database with the updated copy. </ul> <table width="100%"><tr><td><br></td><td align=right><a href="../am/verify.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../am/close.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> </body> </html>