The U.S. Department of Justice may have approved the purchase of Sun Microsystems by Oracle, but the deal still could be delayed by yet another institution. The Brussels-based European Commission still has 48 hours to open an in-depth investigation, reports Reuters, and the DOJ’s European counterparts are looking much more closely at Oracle owning MySQL.

Is a leading enterprise vendor buying out its open source competition a violation of antitrust laws? In its approval the U.S. authorities cited no concern about MySQL, and focused largely on Java licensing issues. Sun’s shareholders voted to go ahead with the multi-billion dollar deal back in July, when it was still under scrutiny from the DOJ.

IBM and HP have wasted no time trying to steal away Sun customers in the server market. By offering financial incentives and implying that Oracle is moving outside its core competency by purchasing a hardware maker, the two companies aim to undercut Oracle during a time of transition.

The European Commission is reportedly still in debate at this time over whether to investigate Oracle more closely. Unlike the DOJ, Reuter’s sources report that the Europeans are concerned over Oracle, a leader in the enterprise database market, owning a key open source competitor.

Since Oracle’s purchase of Sun, interest in MySQL forks has shot up among developers. Prominent examples include MariaDB (created by a co-founder of MySQL) and Drizzle, as well as open source alternative PostgreSQL.