Chapter 4. Information Schema Plugins

The Information Schema was introduced in MySQL 5.0 as a standard way of providing database metadata accessible using normal SELECT queries. To make this work the metadata is made available via read-only tables in a database called INFORMATION_SCHEMA. In the MySQL mailing lists these tables are often informally referred to as I_S tables. The name of the schema, names of tables, and their structure is defined in the SQL standard (ISO/IEC 9075-11:2003 part 11). However, MySQL extends the standard by providing more tables than the standard dictates. This is where plugins come into the game. There is an Information Schema plugin type in MySQL 5.1. Plugins of this type can add new tables to the INFORMATION_SCHEMA database. These plugins are great for exposing information (possibly a lot of it) to the user in tabular form. Often these plugins are not distributed as standalone, but accompany other plugins, for example, complex storage engines, and expose their...