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124 lines
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124 lines
7.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>查询给定的 SQL 会发送给 master、slave 还是最后使用的 MySQL server 执行。</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.mysqlnd-ms-query-is-select" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">mysqlnd_ms_query_is_select</h1>
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<p class="verinfo">(PECL mysqlnd_ms >= 1.0.0)</p><p class="refpurpose"><span class="refname">mysqlnd_ms_query_is_select</span> — <span class="dc-title">查询给定的 SQL 会发送给 master、slave 还是最后使用的 MySQL server 执行。</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.mysqlnd-ms-query-is-select-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>mysqlnd_ms_query_is_select</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$query</code></span>
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) : <span class="type">int</span></div>
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<p class="para rdfs-comment">
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查询给定的 SQL 会发送给 master、slave 还是最后使用的 MySQL server 执行。
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</p>
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<p class="para">
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插件内置的读写分离会分析 SQL，然后决定到底把他发送到哪里执行。这个读写分离器非常
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的基本和简单。插件会将所有的查询发送给 master，除非他以 <em>SELECT</em>
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开头，或者使用 SQL hints 指定要去 slave 执行。因为这个读写分离很简单，
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所以会将一些只读查询发送给主从同步的 master，例如：<em>SHOW TABLES</em>。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.mysqlnd-ms-query-is-select-parameters">
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<h3 class="title">参数</h3>
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<dl>
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<dt>
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<code class="parameter">query</code></dt>
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<dd>
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<p class="para">
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要测试的 SQL 字符串。
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</p>
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</dd>
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</dl>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.mysqlnd-ms-query-is-select-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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返回 <strong><code>MYSQLND_MS_QUERY_USE_MASTER</code></strong> 说明发送给 master。
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返回 <strong><code>MYSQLND_MS_QUERY_USE_SLAVE</code></strong> 说明是一个只读语句，
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将发送给 slave 执行。返回 <strong><code>MYSQLND_MS_QUERY_USE_LAST_USED</code></strong>
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说明会在上一次执行的服务器连接中执行，这可能是 master 也可能是 slave。
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</p>
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<p class="para">
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如果通过设定 <em>mysqlnd_ms.disable_rw_split</em> 禁用了读写分离，
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那么函数可能返回 <strong><code>MYSQLND_MS_QUERY_USE_MASTER</code></strong> 或者返回
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<strong><code>MYSQLND_MS_QUERY_USE_LAST_USED</code></strong>。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.mysqlnd-ms-query-is-select-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-2274">
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<p><strong>Example #1 <span class="function"><strong>mysqlnd_ms_query_is_select()</strong></span> example</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">is_select</span><span style="color: #007700">(</span><span style="color: #0000BB">$query</span><span style="color: #007700">)<br />{<br /> switch (</span><span style="color: #0000BB">mysqlnd_ms_query_is_select</span><span style="color: #007700">(</span><span style="color: #0000BB">$query</span><span style="color: #007700">))<br /> {<br /> case </span><span style="color: #0000BB">MYSQLND_MS_QUERY_USE_MASTER</span><span style="color: #007700">:<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"'%s' should be run on the master.\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$query</span><span style="color: #007700">);<br /> break;<br /> case </span><span style="color: #0000BB">MYSQLND_MS_QUERY_USE_SLAVE</span><span style="color: #007700">:<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"'%s' should be run on a slave.\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$query</span><span style="color: #007700">);<br /> break;<br /> case </span><span style="color: #0000BB">MYSQLND_MS_QUERY_USE_LAST_USED</span><span style="color: #007700">:<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"'%s' should be run on the server that has run the previous query\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$query</span><span style="color: #007700">);<br /> break;<br /> default:<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"No suggestion where to run the '%s', fallback to master recommended\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$query</span><span style="color: #007700">);<br /> break;<br /> }<br />}<br /><br /></span><span style="color: #0000BB">is_select</span><span style="color: #007700">(</span><span style="color: #DD0000">"INSERT INTO test(id) VALUES (1)"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">is_select</span><span style="color: #007700">(</span><span style="color: #DD0000">"SELECT 1 FROM DUAL"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">is_select</span><span style="color: #007700">(</span><span style="color: #DD0000">"/*" </span><span style="color: #007700">. </span><span style="color: #0000BB">MYSQLND_MS_LAST_USED_SWITCH </span><span style="color: #007700">. </span><span style="color: #DD0000">"*/SELECT 2 FROM DUAL"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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INSERT INTO test(id) VALUES (1) should be run on the master.
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SELECT 1 FROM DUAL should be run on a slave.
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/*ms=last_used*/SELECT 2 FROM DUAL should be run on the server that has run the previous query
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.mysqlnd-ms-query-is-select-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member">
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<a href="mysqlnd_ms.constants.html" class="link">Predefined Constants</a>
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</li>
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<li class="member">
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<a href="mysqlnd-ms.plugin-ini-json.html#ini.mysqlnd-ms-plugin-config-v2.filter-user" class="link"><em>user</em></a> filter
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</li>
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</ul>
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<ul class="simplelist">
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<li class="member">
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<a href="mysqlnd_ms.configuration.html" class="link">Runtime configuration</a>
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</li>
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<li class="member">
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<a href="mysqlnd-ms.configuration.html#ini.mysqlnd-ms.disable-rw-split" class="link">mysqlnd_ms.disable_rw_split</a>
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</li>
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<li class="member">
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<a href="mysqlnd-ms.configuration.html#ini.mysqlnd-ms.enable" class="link">mysqlnd_ms.enable</a>
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</li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |