MySQL 5.1 and up supports a plugin API that allows the loading and unloading of server components at runtime, without restarting the server. Currently, the plugin API supports creation of full-text parser plugins. Such a plugin can be used to replace or augment the built-in full-text parser. For example, a plugin can parse text into words using rules that differ from those used by the built-in parser. This can be useful if you need to parse text with characteristics different from those expected by the built-in parser.

The plugin interface is intended as the successor to the older user-defined function (UDF) interface. The plugin interface eventually will include an API for creating UDFs, and it is intended this plugin UDF API will replace the older non-plugin UDF API. After that point, it will be possible for UDFs to be revised for use as plugin UDFs so that they can take advantage of the better security and versioning capabilities of the plugin API. Eventually, support for the older UDF API will be phased out.

The plugin interface requires the plugin table in the mysql database. This table is created as part of the MySQL installation process. If you are upgrading from an older version to MySQL 5.1, you should run the mysql_upgrade command to create this table. See 項4.5.4. 「mysql_upgrade — MySQL アップグレードのテーブル チェック」.