Billionaire Oracle chief Larry Ellison has announced his company's public and private cloud services and a multi-tenant version of his core database product, completing his Saul-like conversion from befuddled skeptic.

The database company's chief executive opened his annual Oracle Open World (OOW) conference announcing a public infrastructure-as-a-service (IaaS) cloud along with a private service, both using Oracle hardware.

Oracle's clouds are thought to be a multi-tenant services, running on a single version of an Oracle database, and will include compute and storage.

The difference between the private and public services is that the public cloud runs in an Oracle data centre while the private version will run on Oracle hardware but on a customer's premises, where it'll be managed by Oracle. Oracle had been expected to announce these IaaS services.

"We own it. We manage it. We upgrade it. You only pay for what you use," Ellison told delegates on Sunday during part one of his customary two-part keynote speech at OOW.

The second keynote comes on Tuesday, where Ellison - who just paid $36.9m on the biggest property deal in California's Malibu this year - is expected to provide more details.

Ellison has come a long way in a short time on cloud computing. In 2008, when cloud hype was rapidly inflating, Oracle's chief rightly highlighted the term's relativity and meaninglessness, skewering Silicon Valley's mindless recategorising of everything as "cloud".

At that time, Ellison reckoned he couldn't see how Oracle could change what it was making or selling in order to capitalise on cloud: "I don't understand what we have to do different, other than change the wording on some our ads," he said.

Four years later, he appears to have recognised that cloud computing means more than just a copy change.

The chief exec also used OOW to complete another conversion. He announced the Oracle 12c database would have multi-tenancy as a major feature. Oracle's chief seems to have overcome his early hostility to multi-tenancy, something he once lambasted Salesforce.com for using as part of its cloud service - which just happens to run on an Oracle database.

Ellison called 12c "the first multi-tenant database in the world".

Back at OOW 2011, you might remember, Ellison attacked Salesforce's model of multi-tenancy, saying: "That's a very bad security model. It's called multi-tenancy 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 virtualised. They put your data at risk by commingling it with others."

When it comes to Oracle, Ellison reckons the database provider's got it right. "I've been very critical of multi-tenancy at the application level. A lot of security features don't work properly when multi-tenancy is implemented at the application level, but they do work properly in Oracle database 12c," Ellison is reported to have said at OOW.

During the remainder of his Sunday-evening show, Ellison continued to romance hardware. The Oracle CEO announced the latest Exadata database server, the X3, running eight-core Intel Xeon processors, with 4TB of storage per rack and a main memory of 40TB of compressed data. ®