Red Hat and many other open-source vendors not only make all of their features and source code available to nonpaying users, but do so early in the development process in order to enlist the aid of those users in testing the code before it is released in product form to paying customers. Those companies primarily earn revenue by offering technical support to users for a fee, which can leave them vulnerable to rival vendors offering support at a lower price, as Oracle is doing via its Unbreakable Linux program for Red Hat users.

In response, a small-but-growing number of open-source vendors are offering software under dual-distribution models, in which certain features are reserved only for paying customers. MySQL already new started down that path last year, when it made some monitoring and load-balancing features as well as the source-code binaries for MySQL Enterprise available only to users with paid subscriptions.

In one of his Slashdot posts this week, Mickos said that Sun has "carefully" considered emulating Red Hat and making all of MySQL's products and technologies openly available.

If the company decides that Red Hat's approach could work for MySQL as well, "we will align our model with theirs," Mickos wrote late Wednesday night. "But we are not absolutely certain that this is the case, and so we are experimenting with other models."

Mickos added that a database like MySQL "behaves somewhat differently in the market" than an operating system like Red Hat Linux does. As a result, "we believe that Red Hat's competitive situation is different from ours," he wrote. "And we are not fully convinced that Red Hat gets a fair compensation in the market for their enormous (and great) investments and contributions."

In yet another post, Mickos acknowledged that the plan to reserve some features for paying customers "will inevitably upset some people." But, he added, "we must make sure that we don't let our operations be subjected to the tyranny of a vocal minority."