From: | Richard Guo <guofenglinux(at)gmail(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Do we need to pass down nonnullable_vars when reducing outer joins? |
Date: | 2022-11-07 02:54:32 |
Message-ID: | CAMbWs4-gXvaZp-EubSAK0-wJosXCSYm+s=W3mNAVR2nP7uERmw@mail.gmail.com |
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Lists: | pgsql-hackers |
On Sun, Nov 6, 2022 at 4:00 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> > AFAICS, the Vars forced nonnullable by given clause are only used to
> > check if we can reduce JOIN_LEFT to JOIN_ANTI, and it is checking the
> > join's own quals there. It seems to me we do not need to pass down
> > nonnullable_vars by upper quals to the children of a join.
>
> Hmm, you are right, we are not doing anything useful with that data.
> I can't remember if I had a concrete plan for doing something with it
> or not, but we sure aren't using it now. So pushed.
Thanks for pushing it!
Thanks
Richard
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