Le Mardi 21 Octobre 2014 10:44 CEST, David Rowley <dgrowle...@gmail.com> a écrit:
> For what it's worth I'd say they are identical, at least, if you discount > deferring foreign key constraints or also executing the query from within > a volatile function which was called by a query which just updated the > user_info table to break referential integrity. I must say I had not thought of that. > The presence of the foreign key on contract_contract.user_info which > references user_user_info.id means that any non-null > contract_contract.user_info record must reference a valid user_user_info > record, therefore the join is not required to prove that a non nulled > user_info contract records match a user info record, therefore the join to > check it exists is pretty much pointless in just about all cases that > you're likely to care about. > > Although, saying that I'm still a bit confused about the question. Are you > asking if there's some way to get PostgreSQL to run the 1st query faster? > Or are you asking if both queries are equivalent? I was asking for a way to make it run faster. Given that it returns at most a few rows found by an index, I was thinking it could be made to run faster. But I agree that the query is not well written (well generated by hibernate) considering the result I want. Regards, Laurent -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
