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Some updates for 1.4

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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@326346 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Ulf Wendel 2012-06-26 13:55:07 +00:00
parent 32de118cd3
commit 579ed5184d
2 changed files with 109 additions and 13 deletions
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13
reference/mysqlnd_ms/book.xml
View file

@ -172,6 +172,13 @@
PHP 5.4.0 or newer: transaction aware when using API calls only to control transactions.
</para>
</listitem>
<listitem>
<para>
Weighted load balancing: servers can be assigned different priorities, for example, to
direct more requests to a powerful machine than to another less powerful machine. Or, to
prefer nearby machines to reduce latency.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
@ -199,6 +206,12 @@
for reading when session consistency is required.
</para>
</listitem>
<listitem>
<para>
Throttling: optionally, the plugin can wait for a slave to become "synchronous" before
continuing.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>

109
reference/mysqlnd_ms/quickstart.xml
View file

@ -610,16 +610,19 @@ $mysqli->close();
<title>Transactions</title>
<para>
The current version of the plugin is not transaction safe by default,
because it is not transaction aware. SQL transactions are
units of work to be run on a single server.
The plugin does not know when the unit of work starts and when it ends.
Therefore, the plugin may decide to switch connections in the middle
of a transaction.
because it is not aware of running transactions in all cases. SQL transactions are
units of work to be run on a single server. The plugin does not always know
when the unit of work starts and when it ends. Therefore, the plugin may
decide to switch connections in the middle of a transaction.
</para>
<para>
No kind of MySQL load balancer can detect transaction boundaries without any
kind of hint from the application.
</para>
<para>
You can either use SQL hints to work around this limitation. Alternatively,
you can activate transaction API call monitoring. In the latter case you
must use API calls only to control transactins, see below.
must use API calls only to control transactions, see below.
</para>
<para>
<example>
@ -698,7 +701,7 @@ $mysqli->close();
plugin to monitor the status of the <literal>autocommit</literal> mode, if
the mode is set by API calls instead of using SQL statements such as
<literal>SET AUTOCOMMIT=0</literal>. This makes it possible for the plugin to
become transaction aware.
become transaction aware. In this case, you do not need to use SQL hints.
</para>
<para>
If using PHP 5.4.0 or newer, API calls that enable <literal>autocommit</literal> mode,
@ -1075,12 +1078,6 @@ PHP Warning: mysqli::query(): (mysqlnd_ms) No connection selected by the last f
</screen>
</example>
</para>
<note>
<title>Fail over logic is work in progress</title>
<para>
The details of the fail over logic may change in future versions.
</para>
</note>
</section>
<section xml:id="mysqlnd-ms.quickstart.gtid">
<title>Global transaction IDs</title>
@ -1700,6 +1697,92 @@ var_dump($res->fetch_assoc());
the cache will not be used and fresh data is read.
</para>
</section>
<section xml:id="mysqlnd-ms.quickstart.failover">
<title>Failover</title>
<para>
By default, the plugin does not attempt to fail over if connecting to a host
fails. This prevents pitfalls related to
<link linkend="mysqlnd-ms.quickstart.connectionpooling">connection state</link>.
It is recommended to manually handle connection errors in a way similar to a failed
transaction. You should catch the error, rebuild the connection state and rerun your
query as shown below.
</para>
<para>
If connection state is no issue to you, you can alternatively enable automatic
and silent failover. Depending on the configuration, the automatic and silent failover
will either attempt to fail over to the master before issuing and error or, try to
connect to other slaves, given the query allowes for it, before attempting to connect
to a master.
</para>
<para>
<example>
<title>Manual failover, automatic optional</title>
<programlisting role="ini">
<![CDATA[
{
"myapp": {
"master": {
"master_0": {
"host": "localhost",
"socket": "\/tmp\/mysql.sock"
}
},
"slave": {
"slave_0": {
"host": "simulate_slave_failure",
"port": "0"
},
"slave_1": {
"host": "127.0.0.1",
"port": 3311
}
},
"filters": { "roundrobin": [] }
}
}
]]>
</programlisting>
</example>
</para>
<para>
<example>
<title>Manual failover</title>
<programlisting role="php">
<![CDATA[
<?php
$mysqli = new mysqli("myapp", "username", "password", "database");
if (!$mysqli)
/* Of course, your error handling is nicer... */
die(sprintf("[%d] %s\n", mysqli_connect_errno(), mysqli_connect_error()));
$sql = "SELECT 1 FROM DUAL";
/* error handling as it should be done regardless of the plugin */
if (!($res = $link->query($sql))) {
/* plugin specific: check for connection error */
switch ($link->errno) {
case 2002:
case 2003:
case 2005:
printf("Connection error - trying next slave!\n");
/* load balancer will pick next slave */
$res = $link->query($sql);
break;
default:
/* no connecion error, failover is unlikely to help */
die(sprintf("SQL error: [%d] %s", $link->errno, $link->error));
break;
}
}
if ($res) {
var_dump($res->fetch_assoc());
}
?>
]]>
</programlisting>
</example>
</para>
</section>
</chapter>
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