[seiji]

To nail down some definitions: C.A.P. = Consistency, Availability, Partition tolerance.

If their goal is hardline 'C,' that means (pedantically) if a partition is detected, the database reports back to the application "database partition exists. denying all reads and writes until resolved."

If you can't tolerate a partition but still want to claim 'A' (where "tolerating" requires merging structured data cleverly with CRDT-like things ("eventually") or last write wins (or even better: random write wins (which is basically a traditional RDBMS approach))), then they can be read-avail and maybe report metadata back to the client you're in read-only mode due to partition crappage and data isn't going to update until partition crappage resolves itself. Look! It's available! I can read from it!

(notably: in Amazon's original Dynamo case, write availability was more important than read availability, which is where ESCAPE comes in ("Eventually Somewhat Consistently Available Partition tolerant Engine"))