Hi út 22. 7. 2025 v 0:12 odesílatel Vik Fearing <v...@postgresfriends.org> napsal:
> > On 21/07/2025 23:29, Matheus Alcantara wrote: > > On Mon Jul 21, 2025 at 5:23 PM -03, Vik Fearing wrote: > >> On 21/07/2025 14:47, Matheus Alcantara wrote: > >>> Hi all, > >>> > >>> I'm sending a proof-of-concept patch to add support for the QUALIFY > >>> clause in Postgres. This feature allows filtering rows after window > >>> functions are computed, using a syntax similar to the WHERE or HAVING > >>> clauses. > >> > >> I took a very brief look at this, and I think your grammar is wrong. > >> The QUALIFY clause should go after the WINDOW clause, just like > >> FROM/WHERE and GROUP BY/HAVING. > >> > >> > >> That is what I am proposing to the standards committee, and I already > >> have some buy-in for that. > >> > > Thank you for the brief review and for the comments! > > > > I'm not sure if I fully understand but please see the new attached > > version. > > > That is my preferred grammar, thank you. I have not looked at the C > code by this can be obtained with a syntax transformation. To wit: > > > SELECT a, b, c > FROM tab > QUALIFY wf() OVER () = ? > > > can be rewritten as: > > > SELECT a, b, c > FROM ( > SELECT a, b, c, wf() OVER () = ? AS qc > FROM tab > ) AS q > WHERE qc > > > and then let the optimizer take over. The standard does this kind of > thing all over the place; I don't know what the postgres project's > position on doing things like this are. > just for curiosity - why the HAVING clause was not used? Any window functions are +/- an "aggregate" function, and then HAVING looks more natural to me. Regards Pavel > -- > > Vik Fearing > > > >
