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359 lines
11 KiB
XML
359 lines
11 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<book xml:id="book.mysqlnd-ms" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>Mysqlnd replication and load balancing plugin</title>
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<titleabbrev>mysqlnd_ms</titleabbrev>
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<preface xml:id="intro.mysqlnd-ms">
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&reftitle.intro;
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<para>
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The mysqlnd replication and load balancing plugin (<literal>mysqlnd_ms</literal>)
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adds easy to use MySQL replication support to all PHP MySQL extensions that use
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<link linkend="book.mysqlnd">mysqlnd</link>.
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</para>
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<para>
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As of version PHP 5.3.3 the MySQL native driver for PHP
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(<literal>mysqlnd</literal>)
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features an internal plugin C API. C plugins, such as the replication and
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load balancing plugin, can extend the functionality of
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<link linkend="book.mysqlnd">mysqlnd</link>.
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</para>
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<para>
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The MySQL native driver for PHP is a C library that ships together with
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PHP as of PHP 5.3.0. It serves as a drop-in replacement for the
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MySQL Client Library (libmysqlclient). Using mysqlnd has
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several advantages: no extra downloads are required because it's bundled with PHP,
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it's under the PHP license, there is lower memory consumption in certain cases, and
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it contains new functionality such as asynchronous queries.
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</para>
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<para>
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Mysqlnd plugins like <literal>mysqlnd_ms</literal> operate, for the most part,
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transparently from a user perspective. The replication and load balancing
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plugin supports all PHP applications, and all MySQL PHP extensions.
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It does not change existing APIs. Therefore, it can easily be used with
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existing PHP applications.
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</para>
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<section xml:id="mysqlnd-ms.key-features">
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<title>Key Features</title>
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<para>
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The key features of PECL/mysqlnd_ms are as follows.
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Transparent and therefore easy to use.
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Supports all of the PHP MySQL extensions.
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</para>
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</listitem>
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<listitem>
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<para>
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SSL support.
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</para>
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</listitem>
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<listitem>
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<para>
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A consistent <acronym>API</acronym>.
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</para>
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</listitem>
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<listitem>
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<para>
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Little to no application changes required, dependent on the required usage scenario.
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</para>
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</listitem>
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<listitem>
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<para>
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Lazy connections: connections to master and slave servers are not
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opened before a SQL statement is executed.
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</para>
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</listitem>
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<listitem>
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<para>
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Optional: automatic use of master after the first write in a web request, to
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lower the possible impact of replication lag.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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Can be used with any MySQL clustering solution.
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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MySQL Replication: Read-write splitting is done by the plugin.
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Primary focus of the plugin.
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</para>
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</listitem>
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<listitem>
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<para>
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MySQL Cluster: Read-write splitting can be disabled.
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Configuration of multiple masters possible
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</para>
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</listitem>
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<listitem>
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<para>
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Third-party solutions: the plugin is optimized for MySQL Replication
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but can be used with any other kind of MySQL clustering solution.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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Featured read-write split strategies
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Automatic detection of SELECT.
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</para>
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</listitem>
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<listitem>
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<para>
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Supports SQL hints to overrule automatism.
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</para>
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</listitem>
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<listitem>
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<para>
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User-defined.
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</para>
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</listitem>
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<listitem>
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<para>
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Can be disabled for, for example, when using synchronous clusters such as MySQL Cluster.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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Featured load balancing strategies
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Round Robin: choose a different slave in round-robin fashion for every slave request.
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</para>
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</listitem>
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<listitem>
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<para>
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Random: choose a random slave for every slave request.
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</para>
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</listitem>
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<listitem>
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<para>
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Random once (sticky): choose a random slave once to run all slave requests for the duration of a web request.
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</para>
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</listitem>
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<listitem>
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<para>
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User-defined. The application can register callbacks with mysqlnd_ms.
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</para>
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</listitem>
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<listitem>
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<para>
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PHP 5.4.0 or newer: transaction aware when using API calls only to control transactions.
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</para>
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</listitem>
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<listitem>
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<para>
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Weighted load balancing: servers can be assigned different priorities, for example, to
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direct more requests to a powerful machine than to another less powerful machine. Or, to
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prefer nearby machines to reduce latency.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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Global transaction ID
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Client-side emulation. Makes manual master server failover and slave promotion easier
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with asynchronous clusters, such as MySQL Replication.
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</para>
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</listitem>
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<listitem>
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<para>
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Support for built-in global transaction identifier feature of MySQL 5.6.5 or newer.
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</para>
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</listitem>
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<listitem>
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<para>
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Supports using transaction ids to identify up-to-date asynchronous slaves
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for reading when session consistency is required. Please, note the restrictions
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mentioned in the manual.
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</para>
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</listitem>
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<listitem>
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<para>
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Throttling: optionally, the plugin can wait for a slave to become "synchronous" before
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continuing.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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Service and consistency levels
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Applications can request eventual, session and strong consistency
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service levels for connections. Appropriate cluster nodes will
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be searched automatically.
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</para>
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</listitem>
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<listitem>
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<para>
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Eventual consistent MySQL Replication slave accesses can be replaced
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with fast local cache accesses transparently to reduce server load.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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Partitioning and sharding
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Servers of a replication cluster can be organized into groups. SQL hints
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can be used to manually direct queries to a specific group.
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Grouping can be used to partition (shard) the data, or to cure the issue of
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hotspots with updates.
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</para>
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</listitem>
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<listitem>
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<para>
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MySQL Replication filters are supported through the table filter.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>
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MySQL Fabric
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</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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<link linkend="mysqlnd-ms.quickstart.mysql_fabric">Experimental support</link>
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for MySQL Fabric is included.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</section>
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<section xml:id="mysqlnd-ms.limitations">
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<title>Limitations</title>
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<para>
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The built-in read-write-split mechanism is very basic. Every
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query which starts with <literal>SELECT</literal>
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is considered a read request to be sent to a MySQL slave server.
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All other queries (such as <literal>SHOW</literal> statements)
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are considered as write requests that are sent to the MySQL master server.
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The build-in behavior can be overruled using
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<link linkend="mysqlnd-ms.constants">SQL hints</link>, or a user-defined
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<link linkend="ini.mysqlnd-ms-plugin-config-v2.filter-user">callback function</link>.
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</para>
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<para>
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The read-write splitter is not aware of multi-statements. Multi-statements
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are considered as one statement. The decision of where to run the statement
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will be based on the beginning of the statement string. For example, if
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using <function>mysqli_multi_query</function>
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to execute the multi-statement <literal>SELECT id FROM test ; INSERT INTO test(id) VALUES (1)</literal>,
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the statement will be redirected to a slave server because it begins with
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<literal>SELECT</literal>. The <literal>INSERT</literal> statement, which is
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also part of the multi-statement, will not be redirected to a master server.
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</para>
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<note>
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<para>
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Applications must be aware of the consequences of connection switches that are
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performed for load balancing purposes. Please check the documentation on
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<link linkend="mysqlnd-ms.pooling">connection pooling and switching</link>,
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<link linkend="mysqlnd-ms.transaction">transaction handling</link>,
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<link linkend="mysqlnd-ms.failover">failover</link>
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<link linkend="mysqlnd-ms.loadbalancing">load balancing</link>&listendand;
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<link linkend="mysqlnd-ms.rwsplit">read-write splitting</link>.
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</para>
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</note>
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</section>
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<section xml:id="mysqlnd-ms.name">
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<title>On the name</title>
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<para>
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The shortcut <literal>mysqlnd_ms</literal>
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stands for <literal>mysqlnd master slave plugin</literal>. The name
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was chosen for a quick-and-dirty proof-of-concept. In the beginning
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the developers did not expect to continue using the code base.
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</para>
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</section>
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</preface>
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&reference.mysqlnd-ms.quickstart;
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&reference.mysqlnd-ms.concepts;
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&reference.mysqlnd-ms.setup;
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&reference.mysqlnd-ms.constants;
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&reference.mysqlnd-ms.reference;
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&reference.mysqlnd-ms.changes;
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</book>
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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-minimize-attributes:nil
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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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