As someone who does a lot with hand-coded upsert implementations, I would say that the problems are genuinely hard. I am somewhat on the sidelines. Not only a

As someone who does a lot with hand-coded upsert implementations, I would say that the problems are genuinely hard. I am somewhat on the sidelines. Not only are the problems hard, but the expected behavior is sometimes even difficult to define. The real problem is that if the desired behavior is not nailed down entirely in the first implementation then what will happen when the operation is improved is that it will break stuff. That's I think the strongest argument for waiting. OTOH, the concurrency issues are genuinely hard and there are a large number of applications for whom they don't really apply in the real world. It might seem to be nice to have a canonical syntax. I guess on balance I agree with you but for very different reasons. Once you have an API, you have a contract.