Sun Microsystems founder and chairman Scott McNealy said during the opening keynote at Oracle OpenWorld 2009 in San Francisco that Oracle will boost developer spending.

Meanwhile, Oracle chief executive Larry Ellison joined McNealy on stage to discuss the two firms' product roadmaps.

Oracle's intention to acquire Sun for $7.4bn (£5.1bn) was announced on 20 April, but still has to be approved by the European Commission. Competitors such as IBM and analyst firms like Gartner have described the delay as unsettling for customers wanting to buy hardware and software, because the priorities of the vendors may change after the merger.

The start of the Oracle OpenWorld customer and partner event showed the eagerness of both companies to reassure customers that Sun's core products would be protected and will flourish under Oracle's leadership.

Before McNealy stepped on stage, music blared throughout the Moscone Center auditorium and all the tracks mentioned the word 'sun'. A coincidence? Unlikely.

Jim Shepherd, an analyst at AMR Research, said prior to the keynote that he was interested to hear how much the firms would disclose, as any discussion of post-acquisition strategies runs the risk of lawsuits from key shareholders. " Then again, it is unlike Ellison to play by the rules," he added.

Sun's Sparc processing technology, which has shipped seven million units so far this decade, will be given more investment under Oracle than it currently receives, according to McNealy and Ellison.

Oracle will also spend more money on the Solaris operating system and the MySQL open-source database than Sun does now, the executives said.

McNealy expanded on the importance of MySQL to Oracle. "Larry says it does not compete with the Oracle database. It competes with Microsoft," he said.

Ellison added: "Just like the Sleepycat open-source database that we have owned for years, we will increase investment and spend more, not less, on MySQL. "

Sun's Java computer language was also mentioned at the conference. It was at this point that the head of Java creation at Sun, James Gosling, contributed to the announcements.

"Oracle's fastest growing products of all time use Java code, and Oracle continues to be one of the biggest contributors to the code," he said. "Am I excited? Absolutely. I've never worked for a software company so it will be an adventure."

Ellison claimed that the merger would allow Oracle and Sun to innovate in a similar way to Apple.

"If an engineer can solve hardware problems simultaneously with software problems, they can do very well. There are some advantages of having a single operation," he said. "We can improve Sun's system performance by tightly integrating Oracle software with Sun hardware."

Ellison also suggested that Oracle would double the number of hardware specialists selling and servicing the Sparc and Solaris systems. "Customers have been uncertain, so we felt we had to reassure them," he said.

The US Department of Justice approved Oracle's proposed acquisition of Sun in August, following the backing by Sun stockholders in July.

Oracle said that it expects the purchase to generate more profit than the previous acquisitions of BEA, PeopleSoft and Siebel combined, and that Sun will contribute over $1.5bn (£1bn) to its non-GAAP operating profit in the first year, and more than $2bn (£1.4bn) in its second year.

Oracle uses Sun's Java software to build its Fusion Middleware, and has said that it is the most important software Oracle has attempted to acquire.