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https://github.com/sigmasternchen/php-doc-en
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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@317311 c90b9560-bf6c-de11-be94-00142212c4b1
233 lines
7.8 KiB
XML
Executable file
233 lines
7.8 KiB
XML
Executable file
<?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 which 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 (AKA libmysql/libmysqlclient). Using mysqlnd has
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several advantages: no extra downloads because it comes with PHP,
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PHP license, lower memory consumption in certain cases,
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new functionality such as asynchronous queries. As of PHP 5.4.0, mysqlnd is
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the compile time default library used by all PHP MySQL extensions
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(<link linkend="ref.mysqli">mysqli</link>,
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<link linkend="ref.mysql">mysql</link>,
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<link linkend="ref.pdo-mysql">PDO_MYSQL</link>).
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</para>
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<para>
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Mysqlnd plugins such as the replication and load balancing plugin operate
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mostly transparent from an user perspective. The replication and load balancing
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plugin supports all PHP applications
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and all PHP MySQL 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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<note>
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<para>
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The mysqlnd replication and load balancing plugin is in beta status.
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It is not feature complete.
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</para>
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</note>
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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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<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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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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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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</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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</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 plugin does not support MySQL replication setups with more
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than one master server. An experimental configuration setting
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<link linkend="ini.mysqlnd-ms.multi_master"><literal>mysqlnd_ms.multi_master</literal></link>
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has been introduced in version 1.1.0-beta to find ways for lifting this
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limitation.
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</para>
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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, including, for example, <literal>SHOW</literal>
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statements, are considered as write requests to be sent to the MySQL master server.
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The build-in behaviour can be overruled using
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<link linkend="mysqlnd-ms.constants">SQL hints</link> or an user-defined
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<link linkend="function.mysqlnd-ms-set-user-pick-server">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.
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</para>
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<para>
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Prior to version 1.1.0-beta the plugin did not support native prepared statements.
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Please note that <link linkend="ref.pdo-mysql">PDO_MySQL</link> is using a
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client-side prepared statement emulation by default. Client-side emulated
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prepared statements are fully supported by any version of
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the replication and load balancing plugin because the emulation is not
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using native prepared statements. If you are using PHP based database
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abstraction, please consult the vendor manual to learn if a client-side
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prepared statement emulation is used.
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</para>
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<note>
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<para>
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Application must be aware of the consequences of connection switches performed
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for load balancing purpose. 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> and
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<link linkend="mysqlnd-ms.rwsplit">read-write splitting</link> carefully.
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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-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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