Eric Auchard– Eric Auchard is a Reuters columnist. The opinions expressed are his own —

When Oracle agreed to buy Sun Microsystems for $7.4 billion in April, the headlines made much of the software maker’s decision to enter the computer business 30 years late. At less than 10 per cent of sales, Sun’s software business seemed an afterthought.

But Sun’s software is now center stage after European competition regulators said on Thursday that they would withhold approval for the deal until they finish probing the impact of the Oracle-Sun merger on the database software market. The decision means the transaction faces at least a four-month delay, pushing it into early next year.

Any delay is costly for Oracle. Sun’s sales have plunged as key financial, government and communications customers have held back purchases of computers and storage until Oracle is able to clarify its long-run commitment to Sun hardware and software products.

The commission is debating whether, or under what conditions, to allow Oracle to acquire Sun’s MySQL database software. Given that the business brings in only $100 million in quarterly revenue, less than 1/25th of Sun sales, the easy way out would be for Oracle to jettison MySQL. However, that would be a mistake.