MySQL 5.4 is based on MySQL 5.1 but includes small, high-impact changes to improve MySQL Server performance, particularly with regard to scalability. These changes exploit advances in hardware and CPU design and enable better utilization of existing hardware.

MySQL 5.4 incorporates work from several sources, such as InnoDB Plugin from Oracle Corp., community patches, and modifications developed by MySQL Scalability and Performance Project members and other MySQL engineers. For information about features of InnoDB Plugin, see the InnoDB Plugin Manual at http://www.innodb.com/products/innodb_plugin/plugin-documentation.

The following sections describe the characteristic features of MySQL 5.4 that distinguish it from MySQL 5.1.