Well put. I'm the co-founder of a database startup called FoundationDB. One of our central philosophies is to decouple the logical data models our product suppo

Well put. I'm the co-founder of a database startup called FoundationDB. One of our central philosophies is to decouple the logical data models our product supports from the physical one. In our case, we choose a core data model of an ordered, transactional key-value store, and built layers (http://foundationdb.com/#layers http://foundationdb.com/#layers) from there to expose other data models. However, decoupling the problem this way without true ACID transctions is very difficult. I think this is why there are so many NoSQL databases in the market with so many different data models; without transactions a change to a logical "record" cannot atomically update multiple physical "records" atomically.