<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>DbEnv::set_lg_max()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="lsn.html" title="Chapter 8. The DbLsn Handle" /> <link rel="prev" href="envset_lg_filemode.html" title="DbEnv::set_lg_filemode()" /> <link rel="next" href="envset_lg_regionmax.html" title="DbEnv::set_lg_regionmax()" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DbEnv::set_lg_max()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="envset_lg_filemode.html">Prev</a> </td> <th width="60%" align="center">Chapter 8. The DbLsn Handle </th> <td width="20%" align="right"> <a accesskey="n" href="envset_lg_regionmax.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="envset_lg_max"></a>DbEnv::set_lg_max()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int DbEnv::set_lg_max(u_int32_t lg_max); </pre> <p> Sets the maximum size of a single file in the log, in bytes. Because <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> file offsets are unsigned four-byte values, the set value may not be larger than the maximum unsigned four-byte value. </p> <p> When the logging subsystem is configured for on-disk logging, the default size of a log file is 10MB. </p> <p> When the logging subsystem is configured for in-memory logging, the default size of a log file is 256KB. In addition, the configured log buffer size must be larger than the log file size. (The logging subsystem divides memory configured for in-memory log records into "files", as database environments configured for in-memory log records may exchange log records with other members of a replication group, and those members may be configured to store log records on-disk.) When choosing log buffer and file sizes for in-memory logs, applications should ensure the in-memory log buffer size is large enough that no transaction will ever span the entire buffer, and avoid a state where the in-memory buffer is full and no space can be freed because a transaction that started in the first log "file" is still active. </p> <p> See <a href="../../programmer_reference/log_limits.html" class="olink">Log File Limits</a> for more information. </p> <p> The database environment's log file size may also be configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The syntax of the entry in that file is a single line with the string "set_lg_max", one or more whitespace characters, and the size in bytes. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is read when the database environment is opened, it will silently overrule configuration done before that time. </p> <p> The <code class="methodname">DbEnv::set_lg_max()</code> method configures a database environment, not only operations performed using the specified <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle. </p> <p> The <code class="methodname">DbEnv::set_lg_max()</code> method may be called at any time during the life of the application. </p> <p> If no size is specified by the application, the size last specified for the database region will be used, or if no database region previously existed, the default will be used. </p> <p> The <code class="methodname">DbEnv::set_lg_max()</code> <span> <span> method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8500768"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp8499904"></a>lg_max</h4> </div> </div> </div> <p> The <span class="bold"><strong>lg_max</strong></span> parameter is the size of a single log file, in bytes. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8485864"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">DbEnv::set_lg_max()</code> <span> <span> method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors: </span> </span> </p> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp8514072"></a>EINVAL</h4> </div> </div> </div> <p> If the size of the log file is less than four times the size of the in-memory log buffer; the specified log file size was too large; or if an invalid flag value or parameter was specified. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8512992"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, <a class="link" href="logc.html" title="The DbLogc Handle">DbLogc</a>, <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8475440"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="lsn.html#loglist" title="Logging Subsystem and Related Methods">Logging Subsystem and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="envset_lg_filemode.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="lsn.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="envset_lg_regionmax.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbEnv::set_lg_filemode() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbEnv::set_lg_regionmax()</td> </tr> </table> </div> </body> </html>