In addition to coming up with new applications designed to take advantage of Hana's speed, SAP also has updated major products like BW and its Business Planning and Consolidation module to run on Hana "without disruption." By that, SAP is promising that running those products on Hana will be a simple software upgrade with no tedious changes to the underlying applications. Running on Hana, BW is said by SAP to deliver sub-second query results that would require minutes or hours with BW running on a conventional database. Similarly, Business Planning and Consolidation activities happen in near real-time without requiring data summaries--data aggregations that are usually required by conventional databases.

Oracle walks a fine line in slamming Hana, because Oracle is also pitching the benefits of in-memory in its own products. Kurian walked this line during Friday's webinar because on the one hand he was touting Oracle's in-memory database, TimesTen, and its supporting appliance, Exalytics, while also slamming Hana. Early on, for example, Kurian noted that DRAM costs have shrunk by 25 times over the past 10 years and he said in-memory response times are "50,000 times faster than going to disk." Yet at the conclusion of the webinar, Kurian asserted that "in-memory is an additional technology that helps people get more value from their databases, but it is not meant to be a replacement for their databases."

It's this is the kind of remark that has led SAP to accuse Oracle of trying to preserve the past and, with it, all the lucrative database licenses it has in place. Where SAP says a single Hana database will eventually run both BW and core transactional applications, Oracle Exalytics is an add-on product (for all but the smallest data marts with less than a terabyte of data). That means an SAP customer running Oracle will still need one database license for the transactional database, a separate license for the data warehouse database, and a third database license (either TimesTen, Essbase, or, in some cases, both) for Oracle Exalytics.

[ Want more on Oracle Exalytics? Read Oracle Exalytics: When Late Is Better Than Never. ]

What's more, in Oracle's old-school approach, transactional data is copied from the application environment to the warehouse and yet again to Exalytics if it's needed for hot queries. So that means three layers of servers, storage, integration, and administration of all of the above.

"Not only do you end up with three copies of the data, you have to add the latency required to move data from one copy to the other," says Gartner analyst Don Feinberg. "The real promise of Hana is that when the transaction is done, the data is instantly in the data warehouse and your analytics become real time."

The promise of Hana is compelling: Running transactions and analytics on a single database, cutting out layers of infrastructure, eliminating redundant data aggregations and materialized views, and doing it all with ultra-high performance. The reality check here is that Hana won't be able to run core transactional SAP enterprise applications until late this year at the earliest (it's already running the BusinessOne service, in beta, but that's not core ERP). Even then, the initial release will be in "ramp up" mode, meaning among a select group of customers. General availability might take another six to eight months.

Meanwhile, one of Oracle's key points about Exalytics is that it improves the performance of existing applications--Oracle's entire portfolio of apps as well as third-party apps--without any changes. Yes, the downside of sticking with the status quo is that you'll have to keep paying for all those databases and related infrastructure. But the upside is that you can keep running the old apps while giving them a performance boost. That's another reason why SAP has to show that its new, Hana-based applications aren't just faster (Exalytics can do that); they have to be better and deliver more business value.

Hana can run existing applications just like Exalytics. But SAP is going to the trouble to build new apps because the old ones simply weren't built for real-time decision-support. For example, speeding up query results won't help if you're still looking at yesterday's data. And even if you can tap into data with low latency (which Oracle can do with its GoldenGate data-integration technology), you still might not increase business value if you can't plug real-time insight into real-time actions.

Oracle knows this as well. During a question-and-answer session at Oracle Open World, where Exalytics was announced, a group of Oracle applications executives acknowledged that they would be developing new apps specifically to exploit Exalytics. There's no sign of them as yet, so for now the party line is that all existing Oracle apps work with the new appliance, getting the benefit of faster performance (meaning query acceleration).