> Unless anybody can think of a way to guarantee uniqueness in CouchDB, I > think I am going to abandon the notion of GUARANTEED uniqueness and instead > implementcode to PREFER uniqueness. Then at the end of the day, we can write > some code that will tell us if that 1 in a million chance (i.e. two > simultaneous inserts/updates) left our database in a state where there are > two docs with the same unique field. > > Since the odds are quite low that it will actually happen, I think we can > deal with the times that it happens manually so long as we know about it. > > Sunny >
You have just identified the problem and solution that CouchDB solves with using a traditional RDBMS in a distributed environment. Check out the discussion on the CAP hypothesis (Others call it a theorem, I'm not convinced, but the basic idea is there). Or more succinctly, guaranteed uniqueness requires global state, global state does not scale. HTH, Paul Davis
