The MySQL developer community has released the first public iteration of what will be the next version of MySQL, version 5.5.
MySQL database administrators are encouraged to test MySQL Server 5.5.0-m2, code-named "Betony," though not run it on their production systems yet.

"The new features in this release are of beta quality. As with any other pre-production release, caution should be taken when installing on production level systems or systems with critical data," wrote Jörg Brühe, a Sun Microsystems senior development engineering working on the MySQL build team, in an e-mail announcing the new release sent out to some MySQL-related mailing lists.

Among the new features in MySQL 5.5 are an option for semi-synchronous replication, which ensures that the database transaction is not completed until a backup copy is made of what is being committed. MySQL 5.5 will also support the ANSI/ISO SQL standard method of programmatically returning errors inside SQL procedures, called Signal/Resignal, which some users have called for. The partitioning syntax has also been beefed up, and more support has been added for XML. Bug fixes and various other modifications are included as well.

The new software is the first edition to be released under a new release model, which proponents say will lead to more stable and frequently updated releases. The "-m" suffix designates that this release is a Milestone release, a version of the software with new features being tested. Milestone releases are generally released ahead of the software being made generally available, or GA, in the parlance of the MySQL release model.

"My personal belief is that we have had some room for improvement in the quality of new features released with new versions of MySQL, and that the Milestone Model is a step in the right direction to resolve some of the issues," wrote Sun MySQL Vice President of Community Relations Kaj Arnö, in a blog post.

Though marked as Milestone 2, this version of the software is actually the first to be released for public testing, noted Steve Curry, Sun spokesman, in an e-mail interview.

MySQL 5.5 was built from MySQL 5.4, itself a relatively minor update for MySQL 5.1, the production version of MySQL most widely used today. MySQL 5.4 will no longer get updated. Users of MySQL 5.1 will be encouraged to upgrade to version 5.5, once it is production ready.

A relational database management system, MySQL has been an issue in the ongoing dispute between Oracle, which intends to buy Sun, and the European Union, which has expressed antitrust concerns about the deal. MySQL creator Michael "Monty" Widenius has also expressed displeasure about Oracle owning MySQL, which has been a lower-cost alternative to Oracle's own RDMS for many users. Sun Microsystems maintains a commercial version of MySQL, though the code itself is open source and independent developers contribute to it.

Curry did not estimate a time when the software would be production ready, but said the new release system should speed the development process. MySQL 5.1 was released in GA form in December 2008 and 11 updates have subsequently been issued for the software.