libdb/docs/api_reference/C/envset_lg_max.html

207 lines
8.5 KiB
HTML
Raw Normal View History

2011-09-13 17:44:24 +00:00
<?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>DB_ENV-&gt;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 7.  The DB_LSN Handle" />
<link rel="prev" href="envset_lg_filemode.html" title="DB_ENV-&gt;set_lg_filemode()" />
<link rel="next" href="envset_lg_regionmax.html" title="DB_ENV-&gt;set_lg_regionmax()" />
</head>
<body>
<div xmlns="" class="navheader">
<div class="libver">
<p>Library Version 11.2.5.2</p>
</div>
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DB_ENV-&gt;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 7. 
The DB_LSN 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>DB_ENV-&gt;set_lg_max()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include &lt;db.h&gt;
int
DB_ENV-&gt;set_lg_max(DB_ENV *dbenv, 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 7.  The DB_LSN Handle">DB_LSN</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">DB_ENV-&gt;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 DB_ENV Handle">DB_ENV</a> handle.
</p>
<p>
The <code class="methodname">DB_ENV-&gt;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">DB_ENV-&gt;set_lg_max()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
2011-12-20 00:07:10 +00:00
<h3 class="title"><a id="id3730884"></a>Parameters</h3>
2011-09-13 17:44:24 +00:00
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
2011-12-20 00:07:10 +00:00
<h4 class="title"><a id="id3730869"></a>lg_max</h4>
2011-09-13 17:44:24 +00:00
</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>
2011-12-20 00:07:10 +00:00
<h3 class="title"><a id="id3730726"></a>Errors</h3>
2011-09-13 17:44:24 +00:00
</div>
</div>
</div>
<p>
The <code class="methodname">DB_ENV-&gt;set_lg_max()</code> <span>
<span>
method may fail and return one of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
2011-12-20 00:07:10 +00:00
<h4 class="title"><a id="id3731052"></a>EINVAL</h4>
2011-09-13 17:44:24 +00:00
</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>
2011-12-20 00:07:10 +00:00
<h3 class="title"><a id="id3731034"></a>Class</h3>
2011-09-13 17:44:24 +00:00
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5.  The DB_ENV Handle">DB_ENV</a>,
<a class="link" href="logc.html" title="The DB_LOGC Handle">DB_LOGC</a>,
<a class="link" href="lsn.html" title="Chapter 7.  The DB_LSN Handle">DB_LSN</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
2011-12-20 00:07:10 +00:00
<h3 class="title"><a id="id3730872"></a>See Also</h3>
2011-09-13 17:44:24 +00:00
</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">DB_ENV-&gt;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"> DB_ENV-&gt;set_lg_regionmax()</td>
</tr>
</table>
</div>
</body>
</html>