Sun Microsystems has dropped its unpopular plan to charge for some features -- and their source code -- in its recently acquired MySQL database.

But the company, which bought MySQL in February for US$1 billion, will continue to reserve some features of the open-source database only for paying users, according to a Tuesday blog posting by MySQL vice-president of community relations, Kaj Arno.

"To financially support MySQL's free and open source platform, we have a business model which allows both community and commercial add-ons, and we remain committed to it," Arno wrote. "We believe the model to be useful for both those who spend money to save time, and those who spend time to save money."

The announcement was first made Monday by Sun senior vice-president Marten Mickos during a panel at the CommunityOne conference held in San Francisco in conjunction with Sun's annual JavaOne show.

The plan to charge for backup encryption and compression features in the upcoming version of MySQL incited a revolt within its large and loyal user base, with some accusing Sun of betraying the community that had propelled MySQL to popularity.

MySQL is the most widely used open-source database, with an especially strong uptake among popular Web firms such as Facebook, Google, Yahoo, Craigslist and others. The tradeoff has been that a very small percentage of its users -- one in a thousand, according to then-MySQL CEO Mickos last year -- ever paid the company a dime.

Arno said that charging for backup features was part of MySQL's strategy to boost revenues if it stayed independent and went IPO, and thus preceded Sun's acquisition of Sun. Still, many MySQL users are closely watching for signs Sun is rushing to make its US$1 billion outlay justify itself.

CNET blogger Matt Asay reported last month that MySQL had, according to Sun CEO Jonathan Schwartz, closed a US$10 million deal.

This week's change of plans was not totally unexpected. In online postings to Slashdot as well as Computerworld after the brouhaha, Mickos said Sun was "not yet" committed to close-sourcing and charging for those features.

But Arno said users should "expect Sun/MySQL to continue experimenting with the business model, and with what's offered for the community and what's offered commercial-only. We won't always know the right answer from the beginning, but we want MySQL to be the most popular database for both paying and non-paying users."