In contrast, "you can take any existing Oracle database you have and move it to our cloud," Ellison said. "You can just move it across and it runs unchanged. Oh by the way, you can move it back if you want to. You can move it to the Amazon cloud if you want to. You can do development and test on our cloud and go into production in your data center ... and nothing changes."

"Beware of false clouds," Ellison said, referring to a favorite saying of Salesforce.com CEO Marc Benioff. "That is such good advice. I could not have said it better myself."

Ellison even trashed Salesforce.com's and other SaaS (software-as-a-service) providers' use of multitenant architectures, wherein many customers share a single application instance with their data kept separate. The practice cuts down on system overhead as well as allows vendors to roll out patches and upgrades to many customers at once.

But Oracle's cloud eschews that approach for very good reasons, Ellison said. "That's a very bad security model. It's called multitenancy and it was state of the art 15 years ago. This is 2011. All the modern compute clouds use virtualization as part of their security model. You get a separate virtual machine, your data's in a separate database because it's virtualized. They put your data at risk by commingling it with others."

Ellison's evisceration of Salesforce.com came after the latest at Oracle, which rescheduled an appearance he was to make Wednesday at OpenWorld to Thursday. Benioff loudly characterized the move as a cancellation, drawing much media attention on Tuesday, while Oracle maintained it did so due to overbooking and space problems at the show, which drew some 45,000 people.