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https://github.com/sigmasternchen/php-doc-en
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Stop calling trx_stickiness experimental. It is tested, we have heard no complains. Assorted other minor changes
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@321015 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Ulf Wendel
parent
9f6bae4b5e
commit
3bb8c62d1a
2 changed files with 43 additions and 26 deletions
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@ -15,6 +15,12 @@
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environments we urge you to read additionally the background information from the
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reference sections.
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</para>
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<para>
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The focus is on using PECL mysqlnd_ms for work with an asynchronous MySQL cluster,
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namelys MySQL replication. Generally speaking an asynchronous cluster is more
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difficult to use than a synchronous one. Thus, users of, for example, MySQL Cluster
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will find more information than needed.
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</para>
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<note>
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<para>
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The documentation has been updated to show the syntax used as of version
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@ -526,7 +532,13 @@ $mysqli->close();
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<para>
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SQL hints can also be used to run <literal>SELECT</literal> statements
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on the MySQL master server. This may be desired if the MySQL slave servers
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are typically behind the master, but you need current data from the database.
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are typically behind the master, but you need current data from the cluster.
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</para>
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<para>
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In version 1.2.0 the concept of a service level has been introduced to address
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cases when current data is required. Using a service level requires less attention
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and removes the need of using SQL hints for this use case. Please, find more
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information below in the service level and consistency section.
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</para>
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<para>
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<example>
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@ -598,7 +610,7 @@ $mysqli->close();
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<section xml:id="mysqlnd-ms.quickstart.transactions">
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<title>Transactions</title>
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<para>
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The current version of the plugin is not transaction safe,
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The current version of the plugin is not transaction safe by default,
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because it is not transaction aware. SQL transactions are
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units of work to be run on a single server.
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The plugin does not know when the unit of work starts and when it ends.
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@ -606,7 +618,9 @@ $mysqli->close();
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of a transaction.
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</para>
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<para>
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You must use SQL hints to work around this limitation.
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You can either use SQL hints to work around this limitation. Alternatively,
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you can activate transaction API call monitoring. In the latter case you
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must use API calls only to control transactins, see below.
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</para>
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<para>
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<example>
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@ -689,7 +703,7 @@ $mysqli->close();
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</para>
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<para>
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If using PHP 5.4.0 or newer, API calls that enable <literal>autocommit</literal> mode,
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and when setting the experimental plugin configuration option
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and when setting the plugin configuration option
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<link linkend="ini.mysqlnd-ms-plugin-config-v2.trx_stickiness">trx_stickiness=master</link>,
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the plugin can automatically disable load balancing and connection switches
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for SQL transactions. In this configuration, the plugin stops load balancing
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@ -700,7 +714,7 @@ $mysqli->close();
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</para>
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<para>
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<example>
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<title>Experimental trx_stickiness setting</title>
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<title>Transaction aware load balancing: trx_stickiness setting</title>
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<programlisting role="ini">
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<![CDATA[
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{
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@ -769,11 +783,11 @@ $mysqli->close();
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</example>
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</para>
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<note>
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<title>Experimental PHP 5.4.0+ feature</title>
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<title>Version requirement</title>
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<para>
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The plugin configuration option
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<link linkend="ini.mysqlnd-ms-plugin-config-v2.trx_stickiness">trx_stickiness=master</link>
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is an experimental feature, and requires PHP 5.4.0 or newer.
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requires PHP 5.4.0 or newer.
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</para>
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</note>
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</section>
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@ -782,7 +796,7 @@ $mysqli->close();
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<note>
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<title>Version requirement</title>
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<para>
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Service levels have been introduced in mysqlnd_ms version 1.2.0-alpha.
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Service levels have been introduced in PECL mysqlnd_ms version 1.2.0-alpha.
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<link linkend="function.mysqlnd-ms-set-qos"><function>mysqlnd_ms_set_qos</function></link>
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is available with PHP 5.4.0 or newer.
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</para>
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@ -792,7 +806,7 @@ $mysqli->close();
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data consistency levels to their users. An asynchronous MySQL replication cluster
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offers eventual consistency by default. A read executed on an asynchronous slave
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may return current, stale or no data at all, depending on whether the slave
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has replayed all master changes or not.
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has replayed all changesets from the master or not.
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</para>
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<para>
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Applications using an MySQL replication cluster need to be designed to work
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@ -801,8 +815,8 @@ $mysqli->close();
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allowed to achieve the required quality of service from the cluster.
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</para>
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<para>
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As of PECL/mysqlnd_ms 1.2.0 the plugin is capable of selecting automatically
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MySQL replication nodes that can deliver session consistency or
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As of PECL mysqlnd_ms 1.2.0 the plugin is capable of selecting
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MySQL replication nodes automatically that deliver session consistency or
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strong consistency. Session consistency means that one client can read its writes.
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Other clients may or may not see the clients' write. Strong consistency means
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that all clients will see all writes from the client.
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@ -881,11 +895,17 @@ if (!$res = $mysqli->query("SELECT item, price FROM specials"))
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Read-write splitting logic has been adapted to fulfill the service level.
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</para>
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<para>
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After the application has read its changes from the <literal>orders</literal> table
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it returns to the default service level, which is eventual consistency. Eventual
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consistency puts no restrictions on choosing a node for statement execution.
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Thus, the <literal>SELECT</literal> statement on the <literal>specials</literal>
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table is executed on a slave.
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After the application has read its changes from the <literal>orders</literal> table
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it returns to the default service level, which is eventual consistency. Eventual
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consistency puts no restrictions on choosing a node for statement execution.
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Thus, the <literal>SELECT</literal> statement on the <literal>specials</literal>
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table is executed on a slave.
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</para>
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<para>
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The new functionality supersedes the use of SQL hints and the
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<literal>master_on_write</literal> configuration option. In many cases
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<function>mysqlnd_ms_set_qos</function> is easier to use, more powerful
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improves portability.
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</para>
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<para>
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<example>
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@ -970,7 +990,7 @@ if (!mysqlnd_ms_set_qos($mysqli, MYSQLND_MS_QOS_CONSISTENCY_EVENTUAL))
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Checking <literal>SHOW SLAVE STATUS</literal> for all slaves adds overhead
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to the application. It is an expensive and slow background operation.
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Try to minimize the use of it. Unfortunately, a MySQL replication cluster
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does not give clients the possibility to request a list of candidates
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does not give clients the possibility to request a list of candidates
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from a central instance.
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Thus, a more efficient way of checking the slaves lag is not available.
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</para>
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@ -981,10 +1001,10 @@ if (!mysqlnd_ms_set_qos($mysqli, MYSQLND_MS_QOS_CONSISTENCY_EVENTUAL))
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</note>
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<para>
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To prevent mysqlnd_ms from emitting a warning if no slaves can be found
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that lag no more than four seconds behind the master, it is necessary to
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enable master fail over in the plugins configuration file. If no slaves
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can be found and fail over is turned on, the plugin picks a master for
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executing the statement.
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that lag no more than the defined number of seconds behind the master,
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it is necessary to enable master fail over in the plugins configuration file.
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If no slaves can be found and fail over is turned on, the plugin
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picks a master for executing the statement.
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</para>
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<para>
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If no slave can be found and fail over is turned off, the plugin emits
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@ -47,7 +47,7 @@
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</para>
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<para>
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Using and parsing <acronym>JSON</acronym> is efficient, and using <acronym>JSON</acronym>
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makes it easier to express hierarchical data structures than the standard
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makes it easier to express hierarchical data structures than the standard
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<filename>php.ini</filename> format.
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</para>
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<para>
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@ -198,7 +198,7 @@ $mysqli = new mysqli("localhost", "username", "password", "database");
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<para xml:id="mysqlnd-ms.plugin-ini-json.server_list_syntax">
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Each configuration section contains, at a minimum, a list of master servers
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and a list of slave servers. The master list is configured with the keyword
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<literal>master</literal>, while the slave list is configured with the
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<literal>master</literal>, while the slave list is configured with the
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<literal>slave</literal> keyword. Failing to provide a slave list will result
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in a fatal <constant>E_WRROR</constant> level error, although a slave list
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may be empty.
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@ -1271,9 +1271,6 @@ User has connected to 'myapp'...
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Transaction stickiness policy. Supported policies:
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<literal>disabled</literal> (default), <literal>master</literal>.
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</para>
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<para>
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Experimental feature.
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</para>
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<para>
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The setting requires 5.4.0 or newer. If used with PHP older than 5.4.0,
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the plugin will emit a warning like
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