This section describes the general MySQL development history, provides an overview about features that have been implemented in previous series and that are new in MySQL 5.5, the release series covered in this manual. The maturity level this release series is general availability. Information about maturity levels can be found in Section 2.1.2.1, “Choosing Which Version of MySQL to Install”.
Before upgrading from one release series to the next, please see the notes in Section 2.13.1, “Upgrading MySQL”.
The most requested features and the versions in which they were implemented are summarized in the following table.
| Feature | MySQL Series |
|---|---|
| Unions | 4.0 |
| Subqueries | 4.1 |
| R-trees | 4.1 (for the MyISAM storage engine) |
| Stored procedures and functions | 5.0 |
| Views | 5.0 |
| Cursors | 5.0 |
| XA transactions | 5.0 |
| Triggers | 5.0 and 5.1 |
| Event scheduler | 5.1 |
| Partitioning | 5.1 |
| Pluggable storage engine API | 5.1 |
| Plugin API | 5.1 |
| InnoDB Plugin | 5.1 |
| Row-based replication | 5.1 |
| Server log tables | 5.1 |
| Scalability and performance improvements | 5.4 |
| DTrace support | 5.4 |
| InnoDB as default storage engine | 5.5 |
| Semisynchronous replication | 5.5 |
| SIGNAL/RESIGNAL support in stored routines | 5.5 |
| Performance Schema | 5.5 |
| Supplementary Unicode characters | 5.5 |