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Quickstart example for node group filter
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@329447 c90b9560-bf6c-de11-be94-00142212c4b1
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Ulf Wendel
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@ -1804,6 +1804,134 @@ if ($res) {
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</example>
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</para>
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</section>
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<section xml:id="mysqlnd-ms.quickstart.partitioning">
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<title>Partitioning and Sharding</title>
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<para>
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Database clustering is done for various reasons. Cluster can improve availability,
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fault tolerance but also to increase performance by applying a divide and conquer approach.
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Work is distributed over many machines. Clustering is sometimes combined with
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partitioning and sharding to further break up a big, complex task into
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smaller, managable units.
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</para>
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<para>
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This plugin aims to support all kinds of MySQL database clusters. Some flavours of
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MySQL database clusters have built-in methods for partitioning and sharding,
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which may or may not be transparent to use. The plugin supports the two most
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common approaches explicitly namely MySQL Replication table filtering and
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application based partitioning or sharding.
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</para>
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<para>
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MySQL Replication supports partitioning in the form of filters that allow you to
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create slaves replicating all database of the master or only certain databases
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respectively tables. It is then in the responsibility of the application
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to choose a slave according to the filter rules. You can either use the
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plugins node_groups filter to manually support this or use
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the experimental table filter.
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</para>
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<para>
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Manual partitioning or sharding is supported through
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node grouping filter and SQL hints since 1.5.0. The node_groups filter
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lets you assign a symbolic name to a group of master and slave servers.
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In the example, the master <literal>master_0</literal> and <literal>slave_0</literal>
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form a group with the name <literal>Partition_A</literal>. It is entirely
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up to you to decide what makes up a group. For example, you may use node
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groups for sharding and use the group name to address shards
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like <literal>Shard_A_Range_0_100</literal>.
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</para>
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<para>
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<example>
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<title>Cluster node groups</title>
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<programlisting role="ini">
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<![CDATA[
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{
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"myapp": {
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"master": {
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"master_0": {
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"host": "localhost",
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"socket": "\/tmp\/mysql.sock"
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}
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},
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"slave": {
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"slave_0": {
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"host": "simulate_slave_failure",
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"port": "0"
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},
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"slave_1": {
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"host": "127.0.0.1",
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"port": 3311
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}
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},
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"filters": {
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"node_groups": {
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"Partition_A" : {
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"master": ["master_0"],
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"slave": ["slave_0"]
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}
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},
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"roundrobin": []
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}
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}
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}
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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<example>
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<title>Manual partitioning using SQL hints</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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function select($mysqli, $msg, $hint = '') {
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/* Note: weak test, two connections to two servers may have the same thread id */
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$sql = sprintf("SELECT CONNECTION_ID() AS _thread, '%s' AS _hint FROM DUAL", $msg);
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if ($hint) {
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$sql = $hint . $sql;
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}
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if (!($res = $mysqli->query($sql))) {
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printf("[%d] %s", $mysqli->errno, $mysqli->error);
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return false;
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}
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$row = $res->fetch_assoc();
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printf("%d - %s - %s\n", $row['_thread'], $row['_hint'], $sql);
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return true;
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}
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$mysqli = new mysqli("myapp", "user", "password", "database");
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if (!$mysqli)
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/* Of course, your error handling is nicer... */
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die(sprintf("[%d] %s\n", mysqli_connect_errno(), mysqli_connect_error()));
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/* All slaves allowed */
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select($mysqli, "slave_0");
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select($mysqli, "slave_1");
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/* only servers of node group "Partition_A" allowed */
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select($mysqli, "slave_1", "/*Partition_A*/");
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select($mysqli, "slave_1", "/*Partition_A*/");
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?>
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]]>
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</programlisting>
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<screen>
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<![CDATA[
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6804 - slave_0 - SELECT CONNECTION_ID() AS _thread, 'slave1' AS _hint FROM DUAL
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2442 - slave_1 - SELECT CONNECTION_ID() AS _thread, 'slave2' AS _hint FROM DUAL
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6804 - slave_0 - /*Partition_A*/SELECT CONNECTION_ID() AS _thread, 'slave1' AS _hint FROM DUAL
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6804 - slave_0 - /*Partition_A*/SELECT CONNECTION_ID() AS _thread, 'slave1' AS _hint FROM DUAL
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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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By default the plugin will use all configured master and slave servers for
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query execution. However, if a query begins with a SQL hint
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<literal>/*node_group*/</literal>,the plugin will consider only the servers
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listed in the <literal>node_group</literal> for query execution. Thus,
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<literal>SELECT</literal> queries prefixed with <literal>/*Partition_A*/</literal>
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are executed on <literal>slave_0</literal> only.
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</para>
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</section>
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</chapter>
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<!-- Keep this comment at the end of the file
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Local variables:
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