The difference between God and Larry Ellison, according to a 1997 book of that title, is that God doesn't think he's Larry Ellison. The Oracle chairman and chief executive is notoriously self-important and difficult to work with.

Nobody would know that better than Ray Lane, Oracle's second-in-command, whose sudden resignation was announced by the software company late last Friday.

Mr Lane, who joined Oracle in 1992, leaving behind a very promising career at Booz-Allen & Hamilton, the technology consulting group, has run the software company on a day-to-day basis for the past four years.

In contrast to his boss, who has a penchant for fast cars, fast yachts, fast planes, expensive art work and a jet-set lifestyle, Mr Lane's tastes are less extravagant.

Although he acknowledged that some of Mr Ellison's expensive style had rubbed off on him, his primary interest over the past few years has been in his new family.

And while Mr Ellison enjoys the role of "visionary" - plotting the future of information technology - Mr Lane has focused on the here-and-now: boosting Oracle's revenues, dealing directly with customers and managing the extraordinarily rapid growth of the company.

During the first two years of Mr Lane's tenure in the executive suite at Oracle's Redwood City, California, headquarters, the chief operating officer often had the view from atop one of the elliptical glass tower buildings pretty much to himself.

His elaborately furnished office, decorated with some of Mr Ellison's expensive Japanese artifacts, reflected the style of his boss, rather than himself.

The matching office on the other side of the building, however, was typically empty.

"This is Larry's office," he said during a visit a couple of years ago, "but he seldom uses it." Instead, Mr Ellison preferred to work at home - a Japanese style enclave - when he was in California.

More often he was travelling the world on speaking engagements or racing his yacht. Mr Ellison's absence drew barbed remarks from some of his competitors to the effect that Oracle lacked a full-time chief executive.

Yet over the past two years, Mr Ellison had become more closely engaged in Oracle's operations.

And while there was no outward sign of animosity between Mr Ellison and Mr Lane, it appeared that the executive suite may have become more crowded than Mr Lane was used to.

Insiders suggest that the most surprising thing about Mr Lane's tenure as president and chief operating officer at Oracle was how long he stayed, rather than his sudden departure.

Many see it as a measure of Mr Lane's character that he was able to withstand the constant demands of his mercurial boss for so long.

It is not as if Mr Lane needed to work at Oracle, or indeed anywhere any more. He amassed a fortune in Oracle stock options as well as picking up a multi-million dollar salary over the past few years. Over the weekend Mr Lane remained "unavailable for comment" according to Oracle officials.

However, the fact that he is to remain a member of Oracle's board of directors suggests that his decision to step out of his management role was reached amicably.

There is no suggestion, as yet, that Mr Lane has accepted or is seeking another job. His continuing membership of Oracle's board would preclude him working for most other large companies in the information technology sector.

Rather, it appears that Mr Lane may have decided to take a break and spend more time with his family.

Married to his former Oracle secretary, Mr Lane has a one-year-old child and another one on the way.