mirror of
https://github.com/yasuhirokimura/db18
synced 2026-06-08 18:29:23 +00:00
Yasuhiro KIMURA
434 lines
19 KiB
HTML
434 lines
19 KiB
HTML
<?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->log_set_config()</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="logput.html" title="DB_ENV->log_put()" />
|
||
<link rel="next" href="logstat.html" title="DB_ENV->log_stat()" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 18.1.40</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">
|
||
<span xmlns="http://www.w3.org/1999/xhtml">DB_ENV->log_set_config()</span>
|
||
|
||
</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="logput.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="logstat.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="envlog_set_config"></a>
|
||
<span>DB_ENV->log_set_config()</span>
|
||
|
||
</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<pre class="programlisting">#include <db.h>
|
||
|
||
int
|
||
DB_ENV->log_set_config(DB_ENV *dbenv, u_int32_t flags, int onoff); </pre>
|
||
<p>
|
||
The <code class="methodname">DB_ENV->log_set_config()</code> method
|
||
configures the Berkeley DB logging subsystem.
|
||
</p>
|
||
<p>
|
||
The <code class="methodname">DB_ENV->log_set_config()</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->log_set_config()</code> method may be
|
||
called at any time during the life of the application.
|
||
</p>
|
||
<p>
|
||
The <code class="methodname">DB_ENV->log_set_config()</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>
|
||
<h3 class="title"><a id="idm139753799744464"></a>Parameters</h3>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div class="sect3" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h4 class="title"><a id="idm139753799743216"></a>flags</h4>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
The <span class="bold"><strong>flags</strong></span> parameter must
|
||
be set by bitwise inclusively
|
||
<span class="bold"><strong>OR</strong></span>'ing together one or
|
||
more of the following values:
|
||
</p>
|
||
<div class="itemizedlist">
|
||
<ul type="disc">
|
||
<li>
|
||
<p><a id="log_set_config_DB_LOG_AUTO_REMOVE"></a>
|
||
<code class="literal">DB_LOG_AUTO_REMOVE</code>
|
||
</p>
|
||
<p>
|
||
If set, Berkeley DB will automatically remove log
|
||
files that are no longer needed.
|
||
</p>
|
||
<p>
|
||
Automatic log file removal is likely to make
|
||
catastrophic recovery impossible.
|
||
</p>
|
||
<p>
|
||
Replication Manager applications operate in a
|
||
group-aware manner for log file removal, and
|
||
automatic log file removal simplifies the
|
||
application.
|
||
</p>
|
||
<p>
|
||
Replication Base API applications will rarely want
|
||
to configure automatic log file removal as it
|
||
increases the likelihood a master will be unable to
|
||
satisfy a client's request for a recent log record.
|
||
</p>
|
||
<p>
|
||
Calling
|
||
<code class="methodname">DB_ENV->log_set_config()</code>
|
||
with the <code class="literal">DB_LOG_AUTO_REMOVE</code> flag
|
||
affects the database environment, including all
|
||
threads of control accessing the database
|
||
environment.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_AUTO_REMOVE</code> flag may
|
||
be used to configure Berkeley DB at any time during
|
||
the life of the application.
|
||
</p>
|
||
</li>
|
||
<li>
|
||
<p><a id="log_set_config_DB_LOG_BLOB"></a>
|
||
<code class="literal">DB_LOG_EXT_FILE</code>
|
||
</p>
|
||
<p>
|
||
Enables full logging of
|
||
<a class="link" href="blob.html" title="Chapter 13. External Files">external file</a> data. Only
|
||
use this flag if using replication or running a hot
|
||
backup; otherwise, it will impose a performance
|
||
penalty on external file operations.
|
||
</p>
|
||
<p>
|
||
This flag is off by default, unless Replication is
|
||
enabled for the environment. In that case, it is
|
||
on by default.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_EXT_FILE</code> flag may be
|
||
used to configure Berkeley DB at any time during
|
||
the life of the application.
|
||
</p>
|
||
</li>
|
||
<li>
|
||
<p><a id="log_set_config_DB_LOG_DIRECT"></a>
|
||
<code class="literal">DB_LOG_DIRECT</code>
|
||
</p>
|
||
<p>
|
||
Turn off system buffering of Berkeley DB log files
|
||
to avoid double caching.
|
||
</p>
|
||
<p>
|
||
Calling
|
||
<code class="methodname">DB_ENV->log_set_config()</code>
|
||
with the DB_LOG_DIRECT flag only affects the
|
||
specified <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
|
||
handle (and any other Berkeley DB handles opened
|
||
within the scope of that handle). For consistent
|
||
behavior across the environment, all
|
||
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handles
|
||
opened in the environment must either set the
|
||
DB_LOG_DIRECT flag or the flag should be specified
|
||
in the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> configuration file.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_DIRECT</code> flag may be
|
||
used to configure Berkeley DB at any time during
|
||
the life of the application.
|
||
</p>
|
||
</li>
|
||
<li>
|
||
<p><a id="log_set_config_DB_LOG_DSYNC"></a>
|
||
<code class="literal">DB_LOG_DSYNC</code>
|
||
</p>
|
||
<p>
|
||
Configure Berkeley DB to flush log writes to the backing disk before
|
||
returning from the write system call, rather than flushing log writes
|
||
explicitly in a separate system call, as necessary. This is only
|
||
available on some systems (for example, systems supporting the
|
||
IEEE/ANSI Std 1003.1 (POSIX) standard O_DSYNC flag, or systems
|
||
supporting the Windows FILE_FLAG_WRITE_THROUGH flag). This flag may
|
||
result in inaccurate file modification times and other file-level
|
||
information for Berkeley DB log files. This flag may offer a
|
||
performance increase on some systems and a performance decrease on
|
||
others.
|
||
</p>
|
||
<p>
|
||
Calling
|
||
<code class="methodname">DB_ENV->log_set_config()</code>
|
||
with the DB_LOG_DSYNC flag only affects the
|
||
specified <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
|
||
handle (and any other Berkeley DB handles opened
|
||
within the scope of that handle). For consistent
|
||
behavior across the environment, all
|
||
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handles
|
||
opened in the environment must either set the
|
||
DB_LOG_DSYNC flag or the flag should be specified
|
||
in the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> configuration file.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_DSYNC</code> flag may be
|
||
used to configure Berkeley DB at any time during
|
||
the life of the application.
|
||
</p>
|
||
</li>
|
||
<li>
|
||
<p><a id="log_set_config_DB_LOG_IN_MEMORY"></a>
|
||
<code class="literal">DB_LOG_IN_MEMORY</code>
|
||
</p>
|
||
<p>
|
||
If set, maintain transaction logs in memory rather
|
||
than on disk. This means that transactions exhibit
|
||
the ACI (atomicity, consistency, and isolation)
|
||
properties, but not D (durability); that is,
|
||
database integrity will be maintained, but if the
|
||
application or system fails, integrity will not
|
||
persist. All database files must be verified
|
||
and/or restored from a replication group master or
|
||
archival backup after application or system
|
||
failure.
|
||
</p>
|
||
<p>
|
||
When in-memory logs are configured and no more log
|
||
buffer space is available, Berkeley DB methods may
|
||
return an additional error value,
|
||
<code class="literal">DB_LOG_BUFFER_FULL</code>. 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>
|
||
Calling
|
||
<code class="methodname">DB_ENV->log_set_config()</code>
|
||
with the <code class="literal">DB_LOG_IN_MEMORY</code> flag
|
||
affects the database environment, including all
|
||
threads of control accessing the database
|
||
environment.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_IN_MEMORY</code> flag may be
|
||
used to configure Berkeley DB only before the
|
||
<a class="xref" href="envopen.html" title="DB_ENV->open()">
|
||
<span>DB_ENV->open()</span>
|
||
|
||
</a>
|
||
method is called.
|
||
</p>
|
||
</li>
|
||
<li>
|
||
<p><a id="log_set_config_DB_LOG_NOSYNC"></a>
|
||
<code class="literal">DB_LOG_NOSYNC</code>
|
||
</p>
|
||
<p>
|
||
If set, the transaction log is not flushed from the
|
||
operating system cache to stable storage when a
|
||
transaction commits or the logging system switches
|
||
log files. This can further increase performance
|
||
when all of the applications in an environment use
|
||
less-than-durable transactions (DB_TXN_NOSYNC and
|
||
DB_TXN_WRITE_NOSYNC).
|
||
</p>
|
||
<p>
|
||
Turning on <code class="literal">DB_LOG_NOSYNC</code> removes
|
||
the durability guarantee of current or future
|
||
DB_TXN_SYNC transactions, as well as any
|
||
transactions which have been active since the last
|
||
checkpoint. All database files must be verified
|
||
and/or restored from a replication group master or
|
||
archival backup after system failure.
|
||
</p>
|
||
<p>
|
||
Turning off <code class="literal">DB_LOG_NOSYNC</code> may be
|
||
done at any time. Current and future DB
|
||
DB_TXN_SYNC transactions will return to full ACID
|
||
characteristics once a checkpoint or log file
|
||
switch occurs.
|
||
</p>
|
||
<p>
|
||
Calling
|
||
<code class="methodname">DB_ENV->log_set_config()</code>
|
||
with the <code class="literal">DB_LOG_NOSYNC</code> flag
|
||
affects the database environment, including all
|
||
threads of control accessing the database
|
||
environment.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_NOSYNC</code> flag may be
|
||
used to configure Berkeley DB at any time.
|
||
<a class="xref" href="envopen.html" title="DB_ENV->open()">
|
||
<span>DB_ENV->open()</span>
|
||
|
||
</a>
|
||
method is called.
|
||
</p>
|
||
</li>
|
||
<li>
|
||
<p>
|
||
<code class="literal">DB_LOG_ZERO</code>
|
||
</p>
|
||
<p>
|
||
If set, zero all pages of a log file when that log
|
||
file is created. This has shown to provide greater
|
||
transaction throughput in some environments. The
|
||
log file will be zeroed by the thread which needs
|
||
to re-create the new log file. Other threads may
|
||
not write to the log file while this is happening.
|
||
</p>
|
||
<p>
|
||
Calling
|
||
<code class="methodname">DB_ENV->log_set_config()</code>
|
||
with the <code class="literal">DB_LOG_ZERO</code> flag
|
||
affects only the current environment handle.
|
||
</p>
|
||
<p>
|
||
The <code class="literal">DB_LOG_ZERO</code> flag may be used
|
||
to configure Berkeley DB at any time.
|
||
</p>
|
||
</li>
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
<div class="sect3" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h4 class="title"><a id="idm139753799693392"></a>onoff</h4>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
If the <span class="bold"><strong>onoff</strong></span> parameter is
|
||
zero, the specified flags are cleared; otherwise they are
|
||
set.
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="sect2" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h3 class="title"><a id="idm139753799732160"></a>Errors</h3>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
The <code class="methodname">DB_ENV->log_set_config()</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>
|
||
<h4 class="title"><a id="idm139753799705328"></a>EINVAL</h4>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
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="idm139753799749472"></a>Class</h3>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
|
||
</p>
|
||
</div>
|
||
<div class="sect2" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h3 class="title"><a id="idm139753799706496"></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="logput.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="logstat.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">
|
||
<span>DB_ENV->log_put()</span>
|
||
|
||
</td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top">
|
||
<span>DB_ENV->log_stat()</span>
|
||
|
||
</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|