If you attended this year's Oracle Open World event (and perhaps even if you didn't), you may have formed the impression that the combination of Oracle Database and the latest Exadata database machine, the X3, offers a formidable combo for companies looking to exploit the speed of in-memory database processing. But in a blog post published on a Forbes satellite site on Wednesday, Oracle made it clear that it has yet to deliver in-memory performance with Oracle Database.

The post by Oracle senior communications VP Bob Evans, "Oracle Calls Out Microsoft over Vaporware Fantasy," challenges Microsoft's Nov. 7 announcement of Project Hekaton. Evans, who was formerly editorial director here at InformationWeek, singled out my coverage in the article "Microsoft In-Memory Move Challenges SAP, Oracle", calling my headline "dubious" given that Hekaton won't arrive, as analysts guess, until 2014 or 2015. (Before joining Oracle, Evans held a similar corporate communications role at SAP.)

Evans' blog goes after Microsoft's claims about Hekaton and comparisons that Doug Leland, Microsoft's general manager of SQL Server marketing, made to the Oracle in-memory strategy. In doing so, however, Evans underscores the fact that Oracle, too, has yet to deliver an in-memory strategy tied to its flagship database.

Quoting Oracle database executive Andy Mendelsohn, the piece points out that Oracle's in-memory database is TimesTen, which runs inside the Exalytics appliance (along with an in-memory version of the Essbase database). That box is a sort of analytics turbocharger, and it's plugged into yet another box, Exadata, which runs on Oracle Database. But here was Evans, protesting that Microsoft was disingenuous in suggesting that Oracle is "forcing customers to buy, learn, and manage a separate solution."

[ Here's the article that sparked the discussion. Read Microsoft In-Memory Move Challenges SAP, Oracle. ]

If Oracle Database had in-memory capabilities, you wouldn't need a separate Exalytics box. But Mendelsohn acknowledges that Oracle Database is limited to "some in-memory database features." He doesn't say how or when, but Mendelsohn promises that Oracle "plans to continue to enhance Oracle Database in-memory capabilities."

So on Microsoft's side it's true we have only a beta product and fuzzy delivery date, but on Oracle's side we have a "yeah, we're going to do that, too" promise by one executive. Will the in-memory capabilities planned for Oracle Database handle transactional apps (as Hekaton promises) while Exalytics continues to handle the analytic needs? Mendelsohn didn't say. If the Oracle DB ends up handling both tasks (as SAP Hana can), will the time Exalytics buyers have invested in learning TimesTen and the in-memory version of Essbase have been unnecessary? That's unknown at this point.

The thing is, all these particulars about Oracle's in-memory plans only undermine the gauzy impression Larry Ellison tried to create at Oracle Open World around Exadata X3 as a memory powerhouse. Having finally admitted that the world is turning to memory and away from disks -- something SAP has been saying for three years -- Ellison had all the zeal of a reformed smoker, talking up the "26 terabytes of memory" available in X3. But don't mistake memory for "in-memory." In fact, the vast majority of that capacity (22 TB) is flash, not RAM, and there is a big difference.

"Flash is not memory, and I disagree with Larry Ellison on that totally," Gartner analyst Don Feinberg told InformationWeek last week. "Exadata doesn't give you an in-memory database, it gives you a disk block cache."

The practical difference is that Exadata cache is not as fast as Hana or what Hekaton promises. Until Oracle delivers full in-memory capability as part of Oracle Database, you give up the potential for real-time performance. Nevertheless, as I quoted Feinberg saying last week, "cache is still fast, and for most clients of Exadata, it's going to be fast enough."

So where does that leave Oracle customers? If you want in-memory analytical performance, you'll have to buy the separate Exalytics appliance. If you want in-memory transactional performance, you're out of luck, but Exadata might do.

As for the competition, SAP just announced SAP CRM running on Hana, and Microsoft just announced Hekaton, its plan for in-memory transactional processing. Microsoft previously delivered in-memory data exploration with Microsoft PowerPivot, introduced in 2010, and in-memory data visualization with Power View, introduced in April.

Hekaton will run transactional applications, so you will be able to take a Microsoft SQL Server application and run it in memory without changes. "That's not something you can do with an Oracle application today," said Feinberg.

Oracle has confirmed, by way of Evans' blog, that the company plans to do more with in-memory capabilities within Oracle Database. But we don't know what it will do or when it will do it. With Microsoft we don't have a release date, but at least we have a roadmap.