A Google engineer reported on his blog last week the availability of enhancements to MySQL, the popular open source database. The report came just as about 1,500 customers convened for the MySQL user group conference at the Santa Clara Convention Center, a few miles from Google's Mountain View, Calif., headquarters.

MySQL's Mickos

For Google, the release of such enhancements is unusual because it has seldom supplied any of its changes to open source code in the past, a bone of contention with the open source communities that have provided Linux, Apache, and much of the code on which Google is built. For MySQL, it's a big boost. "This isn't a contribution from somebody who tried something on a weekend," says Zack Urlocker, VP of products for MySQL AB, the company that supports MySQL. Urlocker says Google's changes are likely to find their way into future MySQL releases. "This is from a significant user of MySQL, and [the enhancements] are used every day at Google."

Google doesn't use MySQL in search, but its YouTube subsidiary depends on the database to manage uploaded video, user comments, ratings, and user profiles. Google improved the open source system's replication and mirroring procedures to ensure constant video and data availability at YouTube. Google also uses MySQL in back-end applications, and its mirroring enhancements mean a MySQL database can fail and a backup system will take its place in one second or less. Restarting a solitary database and recovering data after system failure can take from a few minutes to many hours.

TIMING IS EVERYTHING

MySQL AB changed its contributor license pact last November to make it easier--and safer--to incorporate donations to MySQL from outsiders. A contributor has to document the origins of the code submitted so that MySQL AB can indemnify its customers against patent or copyright challenges.

	Helping Hands
	Google's enhancements: >> Improved MySQL's replication procedures across multiple systems >> Expanded MySQL's ability to mirror itself
	IBM's support: >> MySQL will be certified to run on i5OS, the operating system for IBM's System i, formerly known as AS/400

MySQL emerged from the open source community as a read-only database and caught on because of its ability to speedily serve up Web pages at sites such as Slashdot. The MySQL developers added a storage engine, where changes to data could be stored, based on another open source product, InnoDB. Google's upgrades involve enhancements to the InnoDB part of MySQL, so it can keep two distinct database systems tightly in step. With Google's "semisynchronous" replication, a set of changes to data are acknowledged as implemented in a subsidiary database before the primary database commits to them itself. That ensures that a recent update will be available in a subsidiary database if the primary one fails.

MySQL's standard-issue system implements replication in a different, asynchronous manner and, while efficient, the process leaves open the possibility that the two systems will fall out of step if replication fails.

MySQL hasn't displaced the leading databases, Oracle and DB2, in most production settings, but among developers its use has grown rapidly. A survey by market researcher Evans Data indicates MySQL is second only to Microsoft's SQL Server as the developers' database of choice, used by 40% of the 517 respondents.

And Google isn't MySQL's only friend. At the user group conference last week, MySQL AB and IBM announced support for the database on IBM's System i, with DB2 running underneath it as the storage engine instead of InnoDB. MySQL will be certified to run on i5OS, the operating system for System i, formerly known as IBM's AS/400 midrange servers. "We hope this will open up an exciting new generation of online applications," said MySQL AB CEO Marten Mickos, "to take advantage of all the corporate data stored on one of the most reliable and secure platforms in the IT industry."