mirror of
https://github.com/fofolee/uTools-Manuals.git
synced 2025-06-18 13:57:03 +08:00
225 lines
14 KiB
HTML
225 lines
14 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
|
|
<title>Sets the quality of service needed from the cluster</title>
|
|
</head>
|
|
<body class="docs"><div id="layout">
|
|
<div id="layout-content"><div id="function.mysqlnd-ms-set-qos" class="refentry">
|
|
<div class="refnamediv">
|
|
<h1 class="refname">mysqlnd_ms_set_qos</h1>
|
|
<p class="verinfo">(PECL mysqlnd_ms < 1.2.0)</p><p class="refpurpose"><span class="refname">mysqlnd_ms_set_qos</span> — <span class="dc-title">Sets the quality of service needed from the cluster</span></p>
|
|
|
|
</div>
|
|
|
|
<div class="refsect1 description" id="refsect1-function.mysqlnd-ms-set-qos-description">
|
|
<h3 class="title">说明</h3>
|
|
<div class="methodsynopsis dc-description">
|
|
|
|
<span class="methodname"><strong>mysqlnd_ms_set_qos</strong></span>
|
|
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$connection</code></span>
|
|
, <span class="methodparam"><span class="type">int</span> <code class="parameter">$service_level</code></span>
|
|
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$service_level_option</code></span>
|
|
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$option_value</code></span>
|
|
]] ) : <span class="type">bool</span></div>
|
|
|
|
<p class="para rdfs-comment">
|
|
Sets the quality of service needed from the cluster. A database cluster delivers
|
|
a certain quality of service to the user depending on its architecture. A major
|
|
aspect of the quality of service is the consistency level the cluster can offer.
|
|
An asynchronous MySQL replication cluster defaults to eventual consistency for
|
|
slave reads: a slave may serve stale data, current data, or it may have not the
|
|
requested data at all, because it is not synchronous to the master. In a
|
|
MySQL replication cluster, only master accesses can give strong consistency, which
|
|
promises that all clients see each others changes.
|
|
</p>
|
|
<p class="para">
|
|
PECL/mysqlnd_ms hides the complexity of choosing appropriate nodes to achieve
|
|
a certain level of service from the cluster. The
|
|
"Quality of Service" filter implements the necessary logic. The filter can either
|
|
be configured in the plugins configuration file, or at runtime using
|
|
<span class="function"><strong>mysqlnd_ms_set_qos()</strong></span>.
|
|
</p>
|
|
<p class="para">
|
|
Similar results can be achieved with PECL mysqlnd_ms < 1.2.0, if using
|
|
SQL hints to force the use of a certain type of node or using the
|
|
<em>master_on_write</em> plugin configuration option. The first
|
|
requires more code and causes more work on the application side.
|
|
The latter is less refined than using the quality of service filter.
|
|
Settings made through the function call can be reversed, as shown in the example
|
|
below. The example temporarily switches to a higher service level
|
|
(session consistency, read your writes) and returns
|
|
back to the clusters default after it has performed all operations that require the
|
|
better service. This way, read load on the master can be minimized compared to
|
|
using <em>master_on_write</em>, which would continue using the master
|
|
after the first write.
|
|
</p>
|
|
<p class="para">
|
|
Since 1.5.0 calls will fail when done in the middle of a transaction if
|
|
<a href="mysqlnd-ms.plugin-ini-json.html#ini.mysqlnd-ms-plugin-config-v2.trx-stickiness" class="link">transaction stickiness</a>
|
|
is enabled and transaction boundaries have been detected.
|
|
properly.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<div class="refsect1 parameters" id="refsect1-function.mysqlnd-ms-set-qos-parameters">
|
|
<h3 class="title">参数</h3>
|
|
<dl>
|
|
|
|
|
|
<dt>
|
|
<code class="parameter">connection</code></dt>
|
|
|
|
<dd>
|
|
|
|
<p class="para">
|
|
A PECL/mysqlnd_ms connection handle to a MySQL server of the type
|
|
<a href="ref.pdo_mysql.html" class="link">PDO_MYSQL</a>, <a href="book.mysqli.html" class="link">mysqli</a> or
|
|
<a href="book.mysql.html" class="link">ext/mysql</a> for which a service level is to be set.
|
|
The connection handle is obtained when opening a connection with
|
|
a host name that matches a mysqlnd_ms configuration file
|
|
entry using any of the above three MySQL driver extensions.
|
|
</p>
|
|
</dd>
|
|
|
|
|
|
|
|
<dt>
|
|
<code class="parameter">service_level</code></dt>
|
|
|
|
<dd>
|
|
|
|
<p class="para">
|
|
The requested service level: <strong><code>MYSQLND_MS_QOS_CONSISTENCY_EVENTUAL</code></strong>,
|
|
<strong><code>MYSQLND_MS_QOS_CONSISTENCY_SESSION</code></strong> or
|
|
<strong><code>MYSQLND_MS_QOS_CONSISTENCY_STRONG</code></strong>.
|
|
</p>
|
|
</dd>
|
|
|
|
|
|
|
|
<dt>
|
|
<code class="parameter">service_level_option</code></dt>
|
|
|
|
<dd>
|
|
|
|
<p class="para">
|
|
An option to parameterize the requested service level.
|
|
The option can either be <strong><code>MYSQLND_MS_QOS_OPTION_GTID</code></strong>
|
|
or <strong><code>MYSQLND_MS_QOS_OPTION_AGE</code></strong>.
|
|
</p>
|
|
<p class="para">
|
|
The option <strong><code>MYSQLND_MS_QOS_OPTION_GTID</code></strong> can be used
|
|
to refine the service level <strong><code>MYSQLND_MS_QOS_CONSISTENCY_SESSION</code></strong>.
|
|
It must be combined with a fourth function parameter, the
|
|
<code class="parameter">option_value</code>. The <code class="parameter">option_value</code>
|
|
shall be a global transaction ID obtained from
|
|
<span class="function"><a href="mysqlnd_ms_get_last_gtid.html" class="function">mysqlnd_ms_get_last_gtid()</a></span>. If set, the
|
|
plugin considers both master servers and asynchronous slaves for session
|
|
consistency (read your writes). Otherwise, only masters are
|
|
used to achieve session consistency. A slave is considered up-to-date and
|
|
checked if it has already replicated the global transaction ID from
|
|
<code class="parameter">option_value</code>. Please note, searching appropriate slaves
|
|
is an expensive and slow operation. Use the feature sparsely, if the
|
|
master cannot handle the read load alone.
|
|
</p>
|
|
<p class="para">
|
|
The <strong><code>MYSQLND_MS_QOS_OPTION_AGE</code></strong> option can be combined
|
|
with the <strong><code>MYSQLND_MS_QOS_CONSISTENCY_EVENTUAL</code></strong>
|
|
service level, to filter out asynchronous slaves that lag more seconds behind
|
|
the master than <code class="parameter">option_value</code>. If set, the plugin
|
|
will only consider slaves for reading if
|
|
<em>SHOW SLAVE STATUS</em> reports
|
|
<em>Slave_IO_Running=Yes</em>,
|
|
<em>Slave_SQL_Running=Yes</em> and
|
|
<em>Seconds_Behind_Master <= option_value</em>. Please note,
|
|
searching appropriate slaves is an expensive and slow operation.
|
|
Use the feature sparsely in version 1.2.0. Future versions may improve the
|
|
algorithm used to identify candidates. Please, see the MySQL reference
|
|
manual about the precision, accuracy and limitations of the MySQL administrative
|
|
command <em>SHOW SLAVE STATUS</em>.
|
|
</p>
|
|
</dd>
|
|
|
|
|
|
|
|
<dt>
|
|
<code class="parameter">option_value</code></dt>
|
|
|
|
<dd>
|
|
|
|
<p class="para">
|
|
Parameter value for the service level option. See also the
|
|
<code class="parameter">service_level_option</code> parameter.
|
|
</p>
|
|
</dd>
|
|
|
|
|
|
</dl>
|
|
|
|
</div>
|
|
|
|
|
|
<div class="refsect1 returnvalues" id="refsect1-function.mysqlnd-ms-set-qos-returnvalues">
|
|
<h3 class="title">返回值</h3>
|
|
<p class="para">
|
|
Returns <strong><code>TRUE</code></strong> if the connections service level
|
|
has been switched to the requested. Otherwise, returns <strong><code>FALSE</code></strong>
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<div class="refsect1 unknown-returnvaluet" id="refsect1-function.mysqlnd-ms-set-qos-unknown-returnvaluet">
|
|
<h3 class="title">注释</h3>
|
|
<blockquote class="note"><p><strong class="note">Note</strong>:
|
|
<p class="para">
|
|
<span class="function"><strong>mysqlnd_ms_set_qos()</strong></span> requires
|
|
PHP >= 5.4.0 and PECL mysqlnd_ms >= 1.2.0. Internally, it is using
|
|
a <em>mysqlnd</em> library C functionality not available with PHP 5.3.
|
|
</p>
|
|
<p class="para">
|
|
Please note, all MySQL 5.6 production versions do not provide
|
|
clients with enough information to use GTIDs for enforcing session consistency.
|
|
In the worst case, the plugin will choose the master only.
|
|
</p>
|
|
</p></blockquote>
|
|
</div>
|
|
|
|
|
|
<div class="refsect1 examples" id="refsect1-function.mysqlnd-ms-set-qos-examples">
|
|
<h3 class="title">范例</h3>
|
|
<p class="para">
|
|
<div class="example" id="example-2275">
|
|
<p><strong>Example #1 <span class="function"><strong>mysqlnd_ms_set_qos()</strong></span> example</strong></p>
|
|
<div class="example-contents">
|
|
<div class="phpcode"><pre><span style="color: #000000">
|
|
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">/* Open mysqlnd_ms connection using mysqli, PDO_MySQL or mysql extension */<br /></span><span style="color: #0000BB">$mysqli </span><span style="color: #007700">= new </span><span style="color: #0000BB">mysqli</span><span style="color: #007700">(</span><span style="color: #DD0000">"myapp"</span><span style="color: #007700">, </span><span style="color: #DD0000">"username"</span><span style="color: #007700">, </span><span style="color: #DD0000">"password"</span><span style="color: #007700">, </span><span style="color: #DD0000">"database"</span><span style="color: #007700">);<br />if (!</span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">)<br /> </span><span style="color: #FF8000">/* Of course, your error handling is nicer... */<br /> </span><span style="color: #007700">die(</span><span style="color: #0000BB">sprintf</span><span style="color: #007700">(</span><span style="color: #DD0000">"[%d] %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">mysqli_connect_errno</span><span style="color: #007700">(), </span><span style="color: #0000BB">mysqli_connect_error</span><span style="color: #007700">()));<br /><br /></span><span style="color: #FF8000">/* Session consistency: read your writes */<br /></span><span style="color: #0000BB">$ret </span><span style="color: #007700">= </span><span style="color: #0000BB">mysqlnd_ms_set_qos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">, </span><span style="color: #0000BB">MYSQLND_MS_QOS_CONSISTENCY_SESSION</span><span style="color: #007700">);<br />if (!</span><span style="color: #0000BB">$ret</span><span style="color: #007700">)<br /> die(</span><span style="color: #0000BB">sprintf</span><span style="color: #007700">(</span><span style="color: #DD0000">"[%d] %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">errno</span><span style="color: #007700">, </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">error</span><span style="color: #007700">));<br /><br /></span><span style="color: #FF8000">/* Will use master and return fresh data, client can see his last write */<br /></span><span style="color: #007700">if (!</span><span style="color: #0000BB">$res </span><span style="color: #007700">= </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">"SELECT item, price FROM orders WHERE order_id = 1"</span><span style="color: #007700">))<br /> die(</span><span style="color: #0000BB">sprintf</span><span style="color: #007700">(</span><span style="color: #DD0000">"[%d] %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">errno</span><span style="color: #007700">, </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">error</span><span style="color: #007700">));<br /><br /></span><span style="color: #FF8000">/* Back to default: use of all slaves and masters permitted, stale data can happen */<br /></span><span style="color: #007700">if (!</span><span style="color: #0000BB">mysqlnd_ms_set_qos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">, </span><span style="color: #0000BB">MYSQLND_MS_QOS_CONSISTENCY_EVENTUAL</span><span style="color: #007700">))<br /> die(</span><span style="color: #0000BB">sprintf</span><span style="color: #007700">(</span><span style="color: #DD0000">"[%d] %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">errno</span><span style="color: #007700">, </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">error</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?></span>
|
|
</span>
|
|
</pre></div>
|
|
</div>
|
|
|
|
</div>
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<div class="refsect1 seealso" id="refsect1-function.mysqlnd-ms-set-qos-seealso">
|
|
<h3 class="title">参见</h3>
|
|
<p class="para">
|
|
<ul class="simplelist">
|
|
<li class="member">
|
|
<span class="function"><a href="mysqlnd_ms_get_last_gtid.html" class="function" rel="rdfs-seeAlso">mysqlnd_ms_get_last_gtid()</a> - 返回最后的全局同步 ID (GTID)</span>
|
|
</li>
|
|
<li class="member">
|
|
<a href="mysqlnd_ms.qos_consistency.html" class="link">Service level and consistency concept</a>
|
|
</li>
|
|
<li class="member">
|
|
<a href="mysqlnd_ms.filter.html" class="link">Filter concept</a>
|
|
</li>
|
|
</ul>
|
|
</p>
|
|
</div>
|
|
|
|
|
|
</div></div></div></body></html> |