Php/docs/intro.mysqlnd-qc

• PHP Manual
• mysqlnd_qc
• 简介

The mysqlnd query result cache plugin adds easy to use client-side query caching to all PHP MySQL extensions using mysqlnd.

As of version PHP 5.3.3 the MySQL native driver for PHP ( mysqlnd) features an internal plugin C API. C plugins, such as the query cache plugin, can extend the functionality of mysqlnd.

Mysqlnd plugins such as the query cache plugin operate transparent from a user perspective. The cache plugin supports all PHP applications and all PHP MySQL extensions ( mysqli, mysql, PDO_MYSQL). It does not change existing APIs.

No significant application changes are required to cache a query. The cache has two operation modes. It will either cache all queries (not recommended) or only those queries marked with a certain SQL hint (recommended).

Key Features

• Transparent and therefore easy to use
  • supports all PHP MySQL extensions
  • no API changes
  • very little application changes required
• Flexible invalidation strategy
  • Time-to-Live (TTL)
  • user-defined
• Storage with different scope and life-span
  • Default (Hash, process memory)
  • APC
  • MEMCACHE
  • sqlite
  • user-defined
• Built-in slam defense to prevent cache stampeding.

Limitations

The current 1.0.1 release of PECL mysqlnd_qc does not support PHP 5.4. Version 1.1.0-alpha lifts this limitation.

Prepared statements and unbuffered queries are fully supported. Thus, the plugin is capable of caching all statements issued with mysqli or PDO_MySQL, which are the only two PHP MySQL APIs to offer prepared statement support.

On the name

The shortcut mysqlnd_qc stands for mysqlnd query cache plugin. The name was chosen for a quick-and-dirty proof-of-concept. In the beginning the developers did not expect to continue using the code base. Sometimes PECL/mysqlnd_qc has also been called client-side query result set cache.