All-in-memory versus not: mixed storage is winning
Oracle, like Microsoft, may have an edge over all-in-memory purists, like SAP, when it comes to popular sentiment. Yes, the all-in-memory route means there will be no compromises when it comes to performance and data exploration. But even in-memory advocates in the analytics space like MemSQL and VoltDB recognize that there's a need for warm and cool data stored on less-expensive options like Flash and Disk. I've talked to SAP customers who aren't so sure they can get rid of data warehouses because they have lots of historical data or because not everything they do runs inside of SAP.
Oracle CEO Larry Ellison argued "why not put the hot data in memory and leave everything else in flash or disk?" I think that makes sense to many, and with dynamic, intelligent hot/warm/cold loading and data movement (still to come in this in-memory offering) it's possible to get most of the performance gain you need without breaking the bank. SAP would argue that it can size down the total data footprint by storing data only once in a compressed, columnar, in-memory form and drive all uses. But what about historical data or data not flowing from SAP? People know what they have today and just see big dollar signs when they think of putting it all in RAM.