and the only reason why that all works (kafka, kineis, etc) is _because_ they take care of things like "what if the power goes out before we can flush"? And the

and the only reason why that all works (kafka, kineis, etc) is _because_ they take care of things like "what if the power goes out before we can flush"? And the reason why they have to think of those things is because exactly-once-delivery doesn't exist. If it did, they wouldn't have to do anything. There would be no offsets needed. Offsets are needed because exactly-once-delivery doesn't exist and to achieve exactly-once-processing the extra computation is required. Thus the very start of this thread: exactly-once-delivery and exactly-once-processing are different and it matters. If it didn't matter, there would be no offsets that kafka is tracking because everything would just work.