Re: Add semi-join pushdown to postgres_fdw - Mailing list pgsql-hackers

Hi, Alexander!

On Tue, Mar 18, 2025 at 1:13 PM Alexander Pyhalov
<a.pyhalov@postgrespro.ru> wrote:
> Alexander Korotkov писал(а) 2025-03-18 03:27:
> > Hi, Robins!
> >
> > On Tue, Mar 18, 2025 at 2:20 AM Robins Tharakan <tharakan@gmail.com>
> > wrote:
> >> On Mon, 4 Dec 2023 at 07:22, Alexander Korotkov <aekorotkov@gmail.com>
> >> wrote:
> >> >
> >> >
> >> > Now, I think this looks good.  I'm going to push this if no objections.
> >>
> >> After this commit, I began seeing an unexpected ERROR - see this
> >> bug-report.
> >> https://www.postgresql.org/message-id/18852-fb75b88160678f78%40postgresql.org
> >
> > Thank you for pointing.
> > I'll check this in the next couple of days.
> >
>
> It seems conditions, coming from semi-joins, are handled incorrectly
> under left and right join. When deparsing left/right joins and there are
> semi-joins in inner or outer part of the query, the corresponding part
> is deparsed as subquery. And we can't refer subquery vars from above, so
> just should not pull up the restrictinfos. The attached patch does
> exactly this.

Thank you for the fix.  It looks like this fix generally affects
left/right joins, not just semi-joins.  Can you confirm this doesn't
cause regression for other cases?

------
Regards,
Alexander Korotkov
Supabase