Please help to confirm: even with upsert API, there could still happen data override

let's say we have 2 threads to upsert one document with same uid
is it possible that both threads cound identify its a fresh newly doc and both execute insert operation, which will cause one thread override the other's data.

please help to verify if this could happen because I met some problem that only with the explaination could make sense whole things.


can you guys help to share anything useful?

No this can't happen, you will get an error saying that there was a conflict in that case. You can tell elasticsearch to retry in that case with the retry_on_conflict parameter