Although all MySQL code is available under the Gnu GPL (General Public License), the product is developed primarily by full-time employees of MySQL. Furthermore, the MySQL company requests that community developers sign over copyright to their code contributions to the company before those changes become part of the main MySQL code base. This allows the MySQL company to offer a separate, commercial version of its database for enterprise customers who don't want to be bound by the terms of the GPL. Initially, this license structure was used mainly to allow companies to embed the MySQL database into their own products, but the MySQL company was criticized last year for making it more difficult for non-paying customers to download the enterprise version of the database.

By comparison, Sun has been freer with its own code, foregoing separate, commercial versions of its products in favor of a subscription-based enterprise support scheme. PostgreSQL is arguably even more free; it is governed in a much more distributed, community-based fashion than MySQL, and its permissive license even allows proprietary derivatives, such as EnterpriseDB.

Ironically, however, MySQL's stringent intellectual property policy may be precisely what makes it so appealing to Sun. Red Hat Database and Sun's own version of PostgreSQL were merely different retoolings of an existing open source software product, one that customers could just as easily download from elsewhere. To the enterprise IT community at large, however, there's really only one MySQL -- and from now on, that name will be indelibly associated with Sun. Remember, for all Sun's talk about open source, this is a company that banks so heavily on its trademarks that it had its stock ticker symbol changed to JAVA.

Ah, but there's the rub. Sun open-sourced the Java platform in 2006, and while the move has been widely hailed by developers, not everyone in the business community was as thrilled with the idea of Sun giving away its crown jewels. As former Sun vice president Larry Singer put it, "We [at Sun] were spending all of our time and attention ... on things that were important from an intellectual standpoint, important from an innovative standpoint, [but it was] hard to understand how they were going to drive revenue for the company."

So far, MySQL has built a solid business selling open source database software. Whether Sun has the strategic acumen to take that success to the next level, however, remains to be seen. But stay tuned; after all, US$1 billion gives Sun a hell of an incentive.