Oracle acquired the TimesTen technology last June. Oracle saw the in-memory database as a way to extend its enterprise back-end data storage capabilities to high-performance real-time applications such as Interact's. Interact uses Oracle for back-end data storage as well and does not yet interface those databases with TimesTen, but Massey says he plans to do so.

"We need sub-10-millisecond response time, and you can't get that performance out of an Oracle relational database," says Ed McKee, director of applications at Interact. "To get that kind of performance, the amount of iron you'd have to have would be very significant."

On the other hand, he notes, the in-memory TimesTen product isn't suitable for large-scale data archiving. Interact can serve 1 million telephone subscribers with just 2GB of data in memory because only customer balance information is needed online.

Aspect Software Inc. in Westford, Mass., uses TimesTen for call center services. Traditional databases don't have the sub-500-millisecond call- routing capability it requires, says Chief Technology Officer Gary Barnett. Aspect's customers call centers typically have big databases of customer history behind them but cache key information upfront, in memory, for near-instantaneous response to customer requests, he says.

But deciding what data to replicate forward, and how often, can be tricky, Barnett warns. "There's a trade-off. The more data you have [in memory], the more intelligent we can be in routing calls. But the more data in real time, the more expensive it is."