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<title>Introduction</title>
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<h1 class="title">Introduction</h1>
<p class="para">
The mysqlnd query result cache plugin adds easy to use client-side query
caching to all PHP MySQL extensions using
<a href="book.mysqlnd.html" class="link">mysqlnd</a>.
</p>
<p class="para">
As of version PHP 5.3.3 the MySQL native driver for PHP (
<em>mysqlnd</em>)
features an internal plugin C API. C plugins, such as the query cache
plugin, can extend the functionality of
<a href="book.mysqlnd.html" class="link">mysqlnd</a>.
</p>
<p class="para">
Mysqlnd plugins such as the query cache plugin operate transparent
from a user perspective. The cache plugin supports all PHP applications
and all PHP MySQL extensions (
<a href="ref.mysqli.html" class="link">mysqli</a>,
<a href="ref.mysql.html" class="link">mysql</a>,
<a href="ref.pdo-mysql.html" class="link">PDO_MYSQL</a>).
It does not change existing APIs.
</p>
<p class="para">
No significant application changes are required to cache a query.
The cache has two operation modes. It will either cache all
queries (not recommended) or only those queries marked with a
certain SQL hint (recommended).
</p>
<div class="section" id="mysqlnd-qc.key-features">
<h2 class="title">Key Features</h2>
<p class="para">
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
Transparent and therefore easy to use
</p>
<p class="para">
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
supports all PHP MySQL extensions
</p>
</li>
<li class="listitem">
<p class="para">
no API changes
</p>
</li>
<li class="listitem">
<p class="para">
very little application changes required
</p>
</li>
</ul>
</p>
</li>
<li class="listitem">
<p class="para">
Flexible invalidation strategy
</p>
<p class="para">
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
Time-to-Live (TTL)
</p>
</li>
<li class="listitem">
<p class="para">
user-defined
</p>
</li>
</ul>
</p>
</li>
<li class="listitem">
<p class="para">
Storage with different scope and life-span
</p>
<p class="para">
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
Default (Hash, process memory)
</p>
</li>
<li class="listitem">
<p class="para">
<a href="ref.apc.html" class="link">APC</a>
</p>
</li>
<li class="listitem">
<p class="para">
MEMCACHE
</p>
</li>
<li class="listitem">
<p class="para">
sqlite
</p>
</li>
<li class="listitem">
<p class="para">
user-defined
</p>
</li>
</ul>
</p>
</li>
<li class="listitem">
<p class="para">
Built-in slam defense to prevent cache stampeding.
</p>
</li>
</ul>
</p>
</div>
<div class="section" id="mysqlnd-qc.limitations">
<h2 class="title">Limitations</h2>
<p class="para">
The current 1.0.1 release of PECL mysqlnd_qc does
not support PHP 5.4. Version 1.1.0-alpha lifts this limitation.
</p>
<p class="para">
Prepared statements and unbuffered queries are fully supported.
Thus, the plugin is capable of caching all statements issued
with <em>mysqli</em> or <em>PDO_MySQL</em>, which are
the only two PHP MySQL APIs to offer prepared statement support.
</p>
</div>
<div class="section" id="mysqlnd-qc.name">
<h2 class="title">On the name</h2>
<p class="para">
The shortcut <em>mysqlnd_qc</em>
stands for <em>mysqlnd query cache plugin</em>. The name
was chosen for a quick-and-dirty proof-of-concept. In the beginning
the developers did not expect to continue using the code base.
Sometimes PECL/mysqlnd_qc has also been called
<em>client-side query result set cache</em>.
</p>
</div>
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