| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Richard Guo <guofenglinux(at)gmail(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Do we need to pass down nonnullable_vars when reducing outer joins? |
| Date: | 2022-11-05 20:00:47 |
| Message-ID: | 2767582.1667678447@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
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.
regards, tom lane
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