The European Commission could decide to delay Oracle Corp's $7.4 billion acquisition of Sun Microsystems Inc with less than 48 hours to go before a deadline, two sources familiar with the situation said on Tuesday.

The commission antitrust authority is debating whether to approve the deal by Thursday's deadline, amid concern about Oracle getting its hands on Sun's MySQL database, according to the sources.

If the commission decides to open an in-depth investigation of the matter, such a review could take as long as four months, according to commission rules.

That could put Oracle months behind its original plan for closing the deal, giving rivals -- including Hewlett-Packard Co and International Business Machines Corp -- more time to poach hardware customers from Sun, the No. 4 maker of computer servers.

HP and IBM have been offering discounts and other incentives to woo Sun customers since Oracle agreed to buy Sun in April, playing up concerns that software maker Oracle might have trouble running a hardware maker.

Commission officials have yet to decide whether to conduct such an investigation, according to the sources.

U.S. antitrust authorities cleared the deal last week without conditions after initially delaying the decision on concerns about another issue -- licensing of Sun's Java software. U.S. officials did not publicly cite any concerns about the MySQL database.

Oracle shares were unchanged at $21.88 in afternoon Nasdaq trade, while Sun shares fell 4 cents to $9.24

(Editing by Edwin Chan, Phil Berlowitz)