@ianoc @rubanm  Ooooops, sorry, my comment meant the _put_ method, which actually is the unreliable one. Now i understand @ianoc 's comment. This one here cannot be 100% reliable return the old value in any case, but should reliably be eventually consistent even in node failure situations concerning the increment because of that vector clock thing. @rubanm I tested it: sorry, the CAS-style stuff doesn't work for counter columns (at least cqlsh says so). Hm... What i could do is not return until at least the timestamp of the read is at least as high as the write as according to the spec i mentioned these are at least being used internally (and timestamps can be accessed with Hector). Not a 100% guarantee and probably a whole bunch of milliseconds slower. What do you think?