Marten Mickos on Friday told fellow employees that he's resigning from Sun Microsystems, just a few days short of his first anniversary as senior VP of database software. The news was greeted with dismay by those who thought he was going to play a key role in guiding Sun through its transition to an open source company.

"There's a question whether Sun can make money as an open source company. I would take someone who's been highly successful in an area that Sun has been struggling with and give him free rein," said Rod Johnson, CEO of SpringSource and head developer on the open source Spring Java framework project, in an interview.

"I find it worrying that Sun would let him go. ... Marten believes in open source software, but he was pragmatic, he was able to monetize the open source space. If someone who wanted to be part of an open source business didn't find it that exciting to be at Sun, that's a message that doesn't help" Sun's effort to be recognized as a full-fledged, open source company, he said. Johnson was tapped by Sun last November to sit on the executive committee of its Java Community Process, the body that regulates Java's development.

The impact may be more emotional at first than fiscal. MySQL has been part of Sun for nearly a year. The company has built up its MySQL support capability in its technical support staff, and the open source database continues to be downloaded at a rate of more than 10,000 copies a week. Sun has been increasing MySQL support revenue and signed its first multimillion-dollar contract with a MySQL customer in the last quarter.

"I was impressed by what I heard about MySQL performance inside of Sun," said Mike Olson, CEO of Cloudera, a cloud computing startup that counts Mickos as one of its investors. "Marten has done some great stuff at Sun," he said in an interview.

"Any time a leader of Martin's stature leaves, it's a blow, it's a concern," he added.

Sun is in the midst of another reorganization. The first one in November saw the exit of Rich Green, Sun's executive VP for software and an early advocate of Sun's Java/Solaris open source strategy. Barton George, Sun's former Linux strategist who resigned in September, said he expected Mickos "to be part of that retooling and retuning" of Sun's software organization.