In a letter Tuesday to European Commissioner for Competition Neelie Kroes, Stallman -- together with nonprofit organizations Knowledge Ecology International and Open Rights Group -- urged Europe's top antitrust regulator to demand the divestment of MySQL in return for regulatory approval of Oracle's planned purchase of Sun Microsystems.
[ MySQL co-founder and creator Michael "Monty" Widenius has said Oracle should sell the database. | Oracle's Larry Ellison last week offered reassurances that Sun technologies will not go away. | Keep up on the day's tech news headlines with InfoWorld's Today's Headlines: First Look newsletter. ]
"If Oracle is allowed to acquire MySQL, it will predictably limit the development of the functionality and performance of the MySQL software platform, leading to profound harm to those who use MySQL software to power applications," said Stallman in the letter.
Oracle is the biggest competitor in the market for corporate database software. MySQL is an open source database that has been carving out a growing slice of the market at the expense of Oracle, IBM, and Microsoft -- the three principal competitors in the sector.
Sun bought MySQL last year for about $1 billion. Sun was then approached by IBM, but failed to agree to terms of a merger. Earlier this year Oracle stepped in and agreed to terms for a takeover of the struggling Sun.
"We recognize that Oracle's acquisition of Sun may be essential for Sun's survival. However, Oracle should not be allowed to harm consumer interests in the database market by weakening the competition provided by MySQL," Stallman said.
His comments echo those made by Michael "Monty" Widenius, MySQL's founder, in a blog Monday. Widenius called on the European Commission to prohibit Oracle from taking over MySQL.
Widenius was joined by one-time MySQL shareholder and free software activist Florian Mueller, who Tuesday described the prospect of Oracle owning MySQL as being like "putting the fox in charge of the henhouse."
When the Commission opened its in-depth probe of the proposed deal last month, it said it had to examine very carefully the effects on competition in Europe "when the world's leading proprietary database company proposes to take over the world's leading open source database company." It added that MySQL's open source business model wasn't enough to ensure that fair competition would be safeguarded under the deal.
Oracle has claimed that if it doesn't act as a good host for MySQL, businesses could easily "fork" the GPL-based code of MySQL and create a new platform. However, Stallman said that forking MySQL won't be so easy.
Most users obtain MySQL as free software under the GNU General Public License (GPL) version 2. A version 3 exists, and increasingly open source software developers are expected to migrate to it, Stallman said.
There are "fundamental and unavoidable legal obstacles" to combining code from programs licensed under the different GPL versions, he added. Today, MySQL is only available to the public under GPLv2. If other free software developers migrate to GPL version 3, MySQL could find itself isolated from the free software community that has helped develop the database.
"The lack of a more flexible license for MySQL will present considerable barriers to a new forked development path for MySQL," Stallman said.
IBM and Microsoft, the two other large players in the database market, are watching the European merger review closely. However, IBM declined to comment while Microsoft didn't return calls requesting comment.