The mysqlnd memcache plugin (
mysqlnd_memcache) is an PHP
extension for transparently translating SQL into requests for the
MySQL InnoDB Memcached Daemon Plugin (server plugin). It includes
experimental support for the MySQL Cluster Memcached Daemon. The server
plugin provides access to data stored inside MySQL InnoDB (respectively
MySQL Cluster NDB) tables using the Memcache protocol.
This PHP extension, which supports all PHP MySQL extensions that use
mysqlnd, will identify tables exported in
this way and will translate specific SELECT queries into Memcache requests.
This plugin depends on the MySQL InnoDB Memcached Daemon Plugin. It is not provided to be used with a stand-alone Memcached. For a generic query cache using Memcached look at the mysqlnd query cache plugin. For direct Memcache access look at the memcache and memcached extensions.
The MySQL native driver for PHP is a C library that ships together with PHP as of PHP 5.3.0. It serves as a drop-in replacement for the MySQL Client Library (libmysqlclient). Using mysqlnd has several advantages: no extra downloads are required because it's bundled with PHP, it's under the PHP license, there is lower memory consumption in certain cases, and it contains new functionality such as asynchronous queries.
mysqlnd_mmemcache operates, for the most part,
transparently from a user perspective. The mysqlnd memcache
plugin supports all PHP applications, and all MySQL PHP extensions.
It does not change existing APIs. Therefore, it can easily be used with
existing PHP applications.
The MySQL Memcache plugins add key-value style access method for data stored in InnoDB resp. NDB (MySQL Cluster) SQL tables through the Memcache protocol. This type of key-value access if often faster than using SQL.