Commit f09d7496 authored by Nick Kew's avatar Nick Kew
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Add HTML version of manual page for mod_dbd 


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docs/manual/mod/mod_dbd.html

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URI: mod_dbd.html.en

Content-Language: en

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docs/manual/mod/mod_dbd.html.en

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<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><!--

        XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

              This file is generated from xml source: DO NOT EDIT

        XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

      -->

<title>mod_dbd - Apache HTTP Server</title>

<link title="Main stylesheet" type="text/css" media="all" rel="stylesheet" href="../style/css/manual.css" />

<link title="No Sidebar - Default font size" type="text/css" media="all" rel="alternate stylesheet" href="../style/css/manual-loose-100pc.css" />

<link type="text/css" media="print" rel="stylesheet" href="../style/css/manual-print.css" />

<link rel="shortcut icon" href="../images/favicon.ico" /></head>

<body>

<div id="page-header">

<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>

<p class="apache">Apache HTTP Server Version 2.1</p>

<img src="../images/feather.gif" alt="" /></div>

<div class="up"><a href="./"><img src="../images/left.gif" alt="&lt;-" title="&lt;-" /></a></div>

<div id="path">

<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs-project/">Documentation</a> &gt; <a href="../">Version 2.1</a> &gt; <a href="./">Modules</a></div>

<div id="page-content">

<div id="preamble"><h1>Apache Module mod_dbd</h1>

<div class="toplang">

<p><span>Available Languages: </span><a href="../en/mod/mod_dbd.html" title="English">&nbsp;en&nbsp;</a></p>

</div>

<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Manages SQL database connections</td></tr>

<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="module-dict.html#ModuleIdentifier">ModuleIdentifier:</a></th><td>dbd_module</td></tr>

<tr><th><a href="module-dict.html#SourceFile">SourceFile:</a></th><td>mod_dbd.c</td></tr>

<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Version 2.1 and higher</td></tr></table>

<h3>Summary</h3>



    <p>mod_dbd manages SQL database connections using

    <a href="http://people.apache.org/~niq/dbd.html">apr_dbd</a>.

    It provides database connections on request to modules

    requiring SQL database functions, and takes care of

    managing databases with optimal efficiency and scalability

    for both threaded and non-threaded MPMs.</p>

</div>

<div id="quickview"><h3 class="directives">Directives</h3>

<ul id="toc">

<li><img src="../images/down.gif" alt="" /> <a href="#dbdexptime">DBDExptime</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdkeep">DBDKeep</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdmax">DBDMax</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdmin">DBDMin</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdparams">DBDParams</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdpersist">DBDPersist</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdpreparesql">DBDPrepareSQL</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#dbdriver">DBDriver</a></li>

</ul>

<h3>Topics</h3>

<ul id="topics">

<li><img src="../images/down.gif" alt="" /> <a href="#reslist">Connection Pooling</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#API">Apache DBD API</a></li>

<li><img src="../images/down.gif" alt="" /> <a href="#prepared">SQL Prepared Statements</a></li>

</ul></div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="section">

<h2><a id="reslist" name="reslist">Connection Pooling</a></h2>

    <p>This module manages database connections, in a manner

    optimised for the platform.  On non-threaded platforms,

    it provides a persistent connection in the manner of

    classic LAMP (Linux, Apache, Mysql, Perl/PHP/Python).

    On threaded platform, it provides an altogether more

    scalable and efficient <em>connection pool</em>, as

    described in <a href="http://www.apachetutor.org/dev/reslist" title="Connection pooling in Apache">this article at ApacheTutor</a>.

    mod_dbd supersedes the modules presented in that article.</p>

</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="section">

<h2><a id="API" name="API">Apache DBD API</a></h2>

    <p>mod_dbd exports three functions for other modules to use.

    The API is as follows:</p>

<pre><code>typedef struct {

    apr_dbd_t *handle;

    apr_dbd_driver_t *driver;

    apr_hash_t *prepared;

} ap_dbd_t;



/* Export functions to access the database */



/* acquire a connection that MUST be explicitly closed.

 * Returns NULL on error

 */

AP_DECLARE(ap_dbd_t*) ap_dbd_open(apr_pool_t*, server_rec*);



/* release a connection acquired with ap_dbd_open */

AP_DECLARE(void) ap_dbd_close(server_rec*, ap_dbd_t*);



/* acquire a connection that will have the lifetime of a request

 * and MUST NOT be explicitly closed.  Return NULL on error.

 * This is the preferred function for most applications.

 */

AP_DECLARE(ap_dbd_t*) ap_dbd_acquire(request_rec*);



/* Also export them as optional functions for modules that prefer it */

APR_DECLARE_OPTIONAL_FN(ap_dbd_t*, ap_dbd_open, (apr_pool_t*, server_rec*));

APR_DECLARE_OPTIONAL_FN(void, ap_dbd_close, (server_rec*, ap_dbd_t*));

APR_DECLARE_OPTIONAL_FN(ap_dbd_t*, ap_dbd_acquire, (request_rec*));

</code></pre>

</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="section">

<h2><a id="prepared" name="prepared">SQL Prepared Statements</a></h2>

    <p>mod_dbd supports SQL prepared statements on behalf of

    modules that may wish to use them.  Each prepared statement

    must be assigned a name (label), and they are stored in a hash:

    the <code>prepared</code> field of an <code>ap_dbd_t</code>.

    Hash entries are of type <code>apr_dbd_prepared_t</code>

    and can be used in any of the apr_dbd prepared statement

    SQL query or select commands.</p>

    <p>It is up to dbd user modules to use the prepared statements

    and document what statements can be specified in httpd.conf.</p>

</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDExptime" name="DBDExptime">DBDExptime</a> <a id="dbdexptime" name="dbdexptime">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keepalive time for idle connections</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDExptime <var>time-in-seconds</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>Set the time to keep idle connections alive where the number

    of connections specified in DBDKeep has been exceeded (threaded

    platforms only).</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDKeep" name="DBDKeep">DBDKeep</a> <a id="dbdkeep" name="dbdkeep">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum sustainednumber of connections</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDKeep <var>number</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>Set the maximum number of connections per process to be

    sustained, other than for handling peak demand (threaded

    platforms only).</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDMax" name="DBDMax">DBDMax</a> <a id="dbdmax" name="dbdmax">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of connections</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDMax <var>number</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>Set the hard maximum number of connections per process

    (threaded platforms only).</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDMin" name="DBDMin">DBDMin</a> <a id="dbdmin" name="dbdmin">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Minimum number of connections</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDMin <var>number</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>Set the minimum number of connections per process (threaded

    platforms only).</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDParams" name="DBDParams">DBDParams</a> <a id="dbdparams" name="dbdparams">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Parameters for database connection</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDParams <var>param1=value1,param2=value2</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>As required by the underlying driver.  Typically this will be

    used to pass whatever cannot be defaulted amongst username,

    password, database name, hostname and port number for connection.</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDPersist" name="DBDPersist">DBDPersist</a> <a id="dbdpersist" name="dbdpersist">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Whether to use persistent connections</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDPersist <var>[0|1]</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>If set to 0, persistent and pooled connections are disabled.

    A new database connection is opened when requested by a client,

    and closed immediately on release.  This option is for debugging

    and low-usage servers.</p>

    <p>The default is to enable a pool of persistent connections

    (or a single LAMP-style persistent connection in the case of a

    non-threaded server), and should almost always be used in operation.</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDPrepareSQL" name="DBDPrepareSQL">DBDPrepareSQL</a> <a id="dbdpreparesql" name="dbdpreparesql">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define an SQL prepared statement</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDPrepareSQL <var>"SQL statement"</var> <var>label</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>For modules such as authentication that use repeatedly use a

    single SQL statement, optimum performance is achieved by preparing

    the statement at startup rather than every time it is used.

    This directive prepares an SQL statement and assigns it a label.</p>



</div>

<div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div>

<div class="directive-section"><h2><a id="DBDriver" name="DBDriver">DBDriver</a> <a id="dbdriver" name="dbdriver">Directive</a></h2>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Specify an SQL driver</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DBDriver <var>name</var></code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_dbd</td></tr>

</table>

    <p>Selects an apr_dbd driver by name.  The driver must be installed

    on your system (on most systems, it will be a shared object or dll).

    For example, <code>DBDriver mysql</code> will select the MySQL

    driver in apr_dbd_mysql.so.</p>



</div>

</div>

<div class="bottomlang">

<p><span>Available Languages: </span><a href="../en/mod/mod_dbd.html" title="English">&nbsp;en&nbsp;</a></p>

</div><div id="footer">

<p class="apache">Copyright 1995-2005 The Apache Software Foundation or its licensors, as applicable.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>

<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>

</body></html>

docs/manual/mod/mod_dbd.xml

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<usage>

    <p>Selects an apr_dbd driver by name.  The driver must be installed

    on your system (on most systems, it will be a shared object or dll).

    For example, <samp>DBDriver mysql</samp> will select the MySQL

    For example, <code>DBDriver mysql</code> will select the MySQL

    driver in apr_dbd_mysql.so.</p>

</usage>

</directivesynopsis>