<!--$Id: config.so,v 10.20 2006/08/30 10:08:16 bostic Exp $--> <!--Copyright (c) 1997,2007 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB Reference Guide: Configuring logging</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><h3><dl><dt>Berkeley DB Reference Guide:<dd>Logging Subsystem</dl></h3></td> <td align=right><a href="../log/intro.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../log/limits.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p> <h3 align=center>Configuring logging</h3> <p>The aspects of logging that may be configured are the size of the logging subsystem's region, the size of the log files on disk and the size of the log buffer in memory. The <a href="../../api_c/env_set_lg_regionmax.html">DB_ENV->set_lg_regionmax</a> method specifies the size of the logging subsystem's region, in bytes. The logging subsystem's default size is approximately 60KB. This value may need to be increased if a large number of files are registered with the Berkeley DB log manager, for example, by opening a large number of Berkeley DB database files in a transactional application.</p> <p>The <a href="../../api_c/env_set_lg_max.html">DB_ENV->set_lg_max</a> method specifies the individual log file size for all the applications sharing the Berkeley DB environment. Setting the log file size is largely a matter of convenience and a reflection of the application's preferences in backup media and frequency. However, setting the log file size too low can potentially cause problems because it would be possible to run out of log sequence numbers, which requires a full archival and application restart to reset. See <a href="../../ref/log/limits.html">Log file limits</a> for more information.</p> <p>The <a href="../../api_c/env_set_lg_bsize.html">DB_ENV->set_lg_bsize</a> method specifies the size of the in-memory log buffer, in bytes. Log information is stored in memory until the buffer fills up or transaction commit forces the buffer to be written to disk. Larger buffer sizes can significantly increase throughput in the presence of long-running transactions, highly concurrent applications, or transactions producing large amounts of data. By default, the buffer is approximately 32KB.</p> <table width="100%"><tr><td><br></td><td align=right><a href="../log/intro.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../log/limits.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2007 Oracle. All rights reserved.</font> </body> </html>
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