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https://github.com/sigmasternchen/php-doc-en
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Quickstart: how to cache selected queries based on a pattern
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@322215 c90b9560-bf6c-de11-be94-00142212c4b1
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@ -415,8 +415,8 @@
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<example>
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@ -503,7 +503,6 @@ array(4) {
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]]>
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</screen>
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</example>
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</refsect1>
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163
reference/mysqlnd_qc/functions/mysqlnd-qc-set-is-select.xml
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163
reference/mysqlnd_qc/functions/mysqlnd-qc-set-is-select.xml
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<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision: 322131 $ -->
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<refentry xml:id="function.mysqlnd-qc-set-is-select" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>mysqlnd_qc_set_is_select</refname>
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<refpurpose>Installs a callback which decides whether a statement is cached</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>mixed</type>
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<methodname>mysqlnd_qc_set_is_select</methodname>
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<methodparam>
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<type>string</type>
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<parameter>callback</parameter>
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</methodparam>
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</methodsynopsis>
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<para>
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Installs a callback which decides whether a statement is cached.
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</para>
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<para>
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There are several ways of hinting PELC/mysqlnd_qc to cache a query.
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By default, PECL/mysqlnd_qc attempts to cache a if caching of all statements
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is enabled or the query string begins with a certain SQL hint.
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The plugin internally calls a function named <literal>is_select()</literal>
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to find out. This internal function can be replaced with a user-defined callback.
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Then, the user-defined callback is responsible to decide whether the plugin
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attempts to cache a statement. Because the internal function is replaced
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with the callback, the callback gains full control. The callback is free
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to ignore the configuration setting <literal>mysqlnd_qc.cache_by_default</literal>
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and SQL hints.
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</para>
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<para>
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The callback is invoked for every statement inspected by the plugin.
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It is given the statements string as a parameter. The callback returns
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&false; if the statement shall not be cached. It returns &true; to
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make the plugin attempt to cache the statements result set, if any.
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A so-created cache entry is given the default TTL set with the
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PHP configuration directive <literal>mysqlnd_qc.ttl</literal>.
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If a different TTL shall be used, the callback returns a numeric
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value to be used as the TTL.
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</para>
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<para>
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The internal <literal>is_select</literal> function is part of the internal
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cache storage handler interface. Thus, a user-defined storage handler
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offers the same capabilities.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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&no.function.parameters;
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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&return.success;
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<example>
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<para>
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</para>
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<programlisting role="php">
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<![CDATA[
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<?php
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/* callback which decides if query is cached */
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function is_select($query) {
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static $patterns = array(
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/* true - use default from mysqlnd_qc.ttl */
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"@SELECT\s+.*\s+FROM\s+test@ismU" => true,
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/* 3 - use TTL = 3 seconds */
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"@SELECT\s+.*\s+FROM\s+news@ismU" => 3
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);
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/* check if query does match pattern */
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foreach ($patterns as $pattern => $ttl) {
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if (preg_match($pattern, $query)) {
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printf("is_select(%45s): cache\n", $query);
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return $ttl;
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}
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}
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printf("is_select(%45s): do not cache\n", $query);
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return false;
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}
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mysqlnd_qc_set_is_select("is_select");
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/* Connect, create and populate test table */
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$mysqli = new mysqli("host", "user", "password", "schema");
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$mysqli->query("DROP TABLE IF EXISTS test");
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$mysqli->query("CREATE TABLE test(id INT)");
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$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");
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/* cache put */
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$mysqli->query("SELECT id FROM test WHERE id = 1");
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/* cache hit */
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$mysqli->query("SELECT id FROM test WHERE id = 1");
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/* cache put */
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$mysqli->query("SELECT * FROM test");
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?>
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]]>
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</programlisting>
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&examples.outputs;
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<screen>
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<![CDATA[
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is_select( DROP TABLE IF EXISTS test): do not cache
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is_select( CREATE TABLE test(id INT)): do not cache
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is_select( INSERT INTO test(id) VALUES (1), (2), (3)): do not cache
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is_select( SELECT id FROM test WHERE id = 1): cache
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is_select( SELECT id FROM test WHERE id = 1): cache
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is_select( SELECT * FROM test): cache
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]]>
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</screen>
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</example>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member>
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<link linkend="mysqlnd-qc.configuration">Runtime configuration</link>
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</member>
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<member>
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<link linkend="ini.mysqlnd-qc.ttl">mysqlnd_qc.ttl</link>
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</member>
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<member>
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<link linkend="ini.mysqlnd-qc.cache-by-default">mysqlnd_qc.cache_by_default</link>
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</member>
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<member>
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<function>mysqlnd_qc_set_user_handlers</function>
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</member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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@ -661,6 +661,110 @@ Script runtime : 3 seconds
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</para>
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</section>
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<section xml:id="mysqlnd-qc.pattern_based_caching" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>Pattern based caching</title>
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<para>
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An application has three options for telling PECL/mysqlnd_qc whether a particular
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statement shall be used. The most basic approach is to cache all statements by
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setting <literal><link linkend="mysqlnd-qc.configuration">
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mysqlnd_qc.cache_by_default = 1</link></literal>. This apporach is often of little
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practical value. But it enables users to make a quick estimation about
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the maximum performance gains from caching. An application designed to
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use a cache may able to prefix selected statements with the appropriate SQL
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hints. However, altering an applications source code may not always be possible
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or desired, for example, to avoid problems with software updates. Therefore,
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PECL/mysqlnd_qc allows setting a callback which decides if a query is to be
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cached.
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</para>
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<para>
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The callback is installed with the <function>mysqlnd_qc_set_is_select</function>
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function. The callback is given the statement string of every statement
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inspected by the plugin. Then, the callback can decide whether to cache
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the function. The callback is supposed to return <literal>FALSE</literal>
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if the statement shall not be cached. A return value of <literal>TRUE</literal>
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makes the plugin try to add the statement into the cache. The cache entry
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will be given the default TTL (<literal><link linkend="mysqlnd-qc.configuration">
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mysqlnd_qc.ttl</link></literal>). If the callback returns
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a numberical value it is used as the TTL instead of the global default.
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</para>
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<para>
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<example>
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<programlisting role="ini">
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<![CDATA[
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mysqlnd_qc.enable_qc=1
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mysqlnd_qc.collect_statistics=1
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]]>
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</programlisting>
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<programlisting role="php">
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<![CDATA[
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<?php
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/* callback which decides if query is cached */
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function is_select($query) {
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static $patterns = array(
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/* true - use default from mysqlnd_qc.ttl */
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"@SELECT\s+.*\s+FROM\s+test@ismU" => true,
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/* 3 - use TTL = 3 seconds */
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"@SELECT\s+.*\s+FROM\s+news@ismU" => 3
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);
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/* check if query does match pattern */
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foreach ($patterns as $pattern => $ttl) {
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if (preg_match($pattern, $query)) {
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printf("is_select(%45s): cache\n", $query);
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return $ttl;
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}
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}
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printf("is_select(%45s): do not cache\n", $query);
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return false;
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}
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/* install callback */
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mysqlnd_qc_set_is_select("is_select");
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/* Connect, create and populate test table */
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$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
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$mysqli->query("DROP TABLE IF EXISTS test");
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$mysqli->query("CREATE TABLE test(id INT)");
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$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");
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/* cache put */
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$mysqli->query("SELECT id FROM test WHERE id = 1");
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/* cache hit */
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$mysqli->query("SELECT id FROM test WHERE id = 1");
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/* cache put */
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$mysqli->query("SELECT * FROM test");
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$stats = mysqlnd_qc_get_core_stats();
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printf("Cache put: %d\n", $stats['cache_put']);
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printf("Cache hit: %d\n", $stats['cache_hit']);
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?>
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]]>
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</programlisting>
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&examples.outputs;
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<screen>
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<![CDATA[
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is_select( DROP TABLE IF EXISTS test): do not cache
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is_select( CREATE TABLE test(id INT)): do not cache
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is_select( INSERT INTO test(id) VALUES (1), (2), (3)): do not cache
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is_select( SELECT id FROM test WHERE id = 1): cache
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is_select( SELECT id FROM test WHERE id = 1): cache
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is_select( SELECT * FROM test): cache
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Cache put: 2
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Cache hit: 1
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]]>
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</screen>
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</example>
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</para>
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<para>
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The examples callback tests if a statement string matches a pattern.
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If this is the case, it either returns <literal>TRUE</literal> to cache
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the statement using the global default TTL or an alternative TTL.
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</para>
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<para>
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To minimize application changes the callback can put into and registered
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in an auto prepend file.
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</para>
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</section>
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<section xml:id="mysqlnd-qc.slam-defense" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>Slam defense</title>
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<para>
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