Oracle customers including Vodafone and the NHS are to appear at the European Commission’s antitrust enquiry into the software giants proposed acquisition of Sun Microsystems, according to the Financial Times.

They are expected to back Oracle’s claim that its ownership of MySQL, the open source database company Sun acquired in 2008, will not limit customer choice in the database market. The software vendor argues that MySQL servers a different market than its existing database products.

MySQL founder Monty Widenius, who left the company following the Sun deal, is due to support the opposing argument.

Some open source advocates fear that Oracle will ‘kill’ MySQL once it owns the commercial organisations associated with project. Oracle denies this claim, pointing to other open source technologies it has acquired – and maintained – in the past.

Should the EC find the proposed deal anticompetitive, Oracle may be forced to agree to by Sun without MySQL. However, even if the deal gets clearance, its MySQL troubles won’t be over.

In Information Age’s recent profile of Oracle, Gartner analyst Andy Butler explained that the company will have to handle the developer community that surrounds the MySQL project with care if it is to benefit from the acquisition.

“Oracle wants to influence where MySQL is in the competitive landscape to make sure there isn’t competitive friction [with its existing products],” he said, “But creating a close clone of MySQL without any obligation to Oracle will be relatively easy, so they cannot risk alienating the community.”

Last week, Sun Microsystems revealed a 26% decline in revenues for it most recent financial quarter. Reports suggests that Sun customers, uncertain of its future, are looking elsewhere for hardware and systems purchases.