Axmark is an "important figurehead" at MySQL and someone who recruited many of its top engineers, Arno said. But his role lately has been primarily speaking with the press and liasing with the open-source community, according to Arno. Axmark will continue to do consulting and speaking engagements for Sun, he said.

"Emotionally, it's a sad moment to see a cofounder leave -- but the day-to-day impact is low," Arno said via instant message.

Marten Mickos, MySQL's former CEO, continues to lead the database group within Sun, and Jeffrey Pugh is still head of engineering, Arno said.

Axmark couldn't be reached for comment Tuesday. Arno said the things he disliked about being part of a large company were "mundane things" like having to turn in expense reports, order travel and change his e-mail to "@sun.com."