The MySQL 5.5 Community Edition, which is licensed under the GNU GPL, and is available for free download, includes InnoDB as the default storage engine.
With the MySQL 5.5 release users benefit from:
Improved performance and scalability: MySQL Database and InnoDB storage engine have been enhanced to provide optimum performance and scalability when running on the latest multi-CPU and multi-core hardware and operating systems. In addition, with release 5.5, InnoDB is now the default storage engine for the MySQL Database, delivering ACID transactions, referential integrity and crash recovery.
Higher availability: New semi-synchronous replication and Replication Heart Beat improve failover speed and reliability.
Improved usability: Improved index and table partitioning, SIGNAL/RESIGNAL support and enhanced diagnostics, including a new PERFORMANCE_SCHEMA, improve the manageability of MySQL 5.5.
In recent benchmarks, the MySQL 5.5 release candidate delivered significant performance improvements compared to MySQL 5.1. Results included:
- On Windows: Up to 1,500 percent performance gains for Read/Write operations and up to 500 percent gain for Read Only.
- On Linux: Up to 360 percent performance gain in Read/Write operations and up to 200 percent improvement in Read Only.