21.9.10.4. Quickstart and Examples

The mysqlnd memcache plugin is easy to use. This quickstart will demo typical use-cases, and provide practical advice on getting started.

It is strongly recommended to read the reference sections in addition to the quickstart. The quickstart tries to avoid discussing theoretical concepts and limitations. Instead, it will link to the reference sections. It is safe to begin with the quickstart. However, before using the plugin in mission critical environments we urge you to read additionally the background information from the reference sections.

21.9.10.4.1. Setup

The plugin is implemented as a PHP extension. See also the installation instructions to install this extension.

Compile or configure the PHP MySQL extension (API) (mysqli, PDO_MYSQL, mysql). That extension must use the mysqlnd library as because mysqlnd_memcache is a plugin for the mysqlnd library. For additional information, refer to the mysqlnd_memcache installation instructions.

Then, load this extension into PHP and activate the plugin in the PHP configuration file using the PHP configuration directive named mysqlnd_memcache.enable.

Example 21.393. Enabling the plugin (php.ini)

; On Windows the filename is php_mysqnd_memcache.dll; Load the extensionextension=mysqlnd_memcache.so; Enable itmysqlnd_memcache.enable=1

Follow the instructions given in the MySQL Reference Manual on installing the Memcache plugins for the MySQL server. Activate the plugins and configure Memcache access for SQL tables.

The examples in this quickguide assume that the following table exists, and that Memcache is configured with access to it.

Example 21.394. SQL table used for the Quickstart

CREATE TABLE test(  id CHAR(16),  f1 VARCHAR(255),  f2 VARCHAR(255),  f3 VARCHAR(255),  flags INT NOT NULL,  cas_column INT,  expire_time_column INT,  PRIMARY KEY(id)  ) ENGINE=InnoDB;INSERT INTO test (id, f1, f2, f3) VALUES (1, 'Hello', 'World', '!');INSERT INTO test (id, f1, f2, f3) VALUES (2, 'Lady', 'and', 'the tramp');INSERT INTO innodb_memcache.containers(  name, db_schema, db_table, key_columns, value_columns,   flags, cas_column, expire_time_column, unique_idx_name_on_key)VALUES (  'plugin_test', 'test', 'test', 'id', 'f1,f2,f3',  'flags', 'cas_column', 'expire_time_column', 'PRIMARY KEY');

21.9.10.4.2. Usage

After associating a MySQL connection with a Memcache connection using mysqnd_memcache_set the plugin attempts to transparently replace SQL SELECT statements by a memcache access. For that purpose the plugin monitors all SQL statements executed and tries to match the statement string against MYSQLND_MEMCACHE_DEFAULT_REGEXP . In case of a match, the mysqlnd memcache plugin checks whether the SELECT is accessing only columns of a mapped table and the WHERE clause is limited to a single key lookup.

In case of the example SQL table, the plugin will use the Memcache interface of the MySQL server to fetch results for a SQL query like SELECT f1, f2, f3 WHERE id = n.

Example 21.395. Basic example.

<?php$mysqli = new mysqli("host", "user", "passwd", "database");$memc = new Memcached();$memc->addServer("host", 11211);mysqlnd_memcache_set($mysqli, $memc);/*   This is a query which queries table test using id as key in the WHERE part   and is accessing fields f1, f2 and f3. Therefore, mysqlnd_memcache   will intercept it and route it via memcache.*/$result = $mysqli->query("SELECT f1, f2, f3 FROM test WHERE id = 1");while ($row = $result->fetch_row()) {    print_r($row);}/*   This is a query which queries table test but using f1 in the WHERE clause.   Therefore, mysqlnd_memcache can't intercept it. This will be executed   using the MySQL protocol*/$mysqli->query("SELECT id FROM test WHERE f1 = 'Lady'");while ($row = $result->fetch_row()) {    print_r($row);}?>

The above example will output:

array(    [f1] => Hello    [f2] => World    [f3] => !)array(    [id] => 2)