Re: [EXTERNAL]: Re: [EXTERNAL]: Re: UPSERT in Postgres

On 4/9/23 19:55, Louis Tian wrote:
> Hi Alban,
>
> "I am not expecting an error here", by "here" I means when doing a TRUE UPSERT (an upsert current does not exist in Postgres).
> I am NOT referring to an "Insert on conflict do update" (which despite its intention and wide acceptance is not fully equivalent to a true upsert).
> I understand the error I am getting now is due to not null constraint given how "insert on conflict" works.
>
> An UPSERT checks whether a row exists, if so, it does an update, if not it does an insert. This is the literal definition.

This the part that's always eluded me: How does the client, the 
UPSERTer, come to hold an id and not know whether or not it's already in 
the database.