Re: Check each of base restriction clauses for constant-FALSE-or-NULL

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От Richard Guo
Тема Re: Check each of base restriction clauses for constant-FALSE-or-NULL
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Msg-id CAMbWs48-L_Op2UP+bVxc6uA=KoFSOdBRG8srw5n=+FcCqmUCYA@mail.gmail.com
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Ответ на Re: Check each of base restriction clauses for constant-FALSE-or-NULL  (Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>)
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On Tue, Oct 10, 2023 at 1:45 PM Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> wrote:
On Tue, Oct 10, 2023 at 11:09 AM Richard Guo <guofenglinux@gmail.com> wrote:
> Hm, I don't think so.  get_gating_quals is called in createplan.c, where
> we've selected the best path, while the optimization with my code
> happens much earlier, when we set size estimates for a base relation.
> Neither of these two is a duplicate of the other.  I think the theory
> here is that it's always a win to mark a rel as dummy if possible as
> early as we can.

Right. Do you have an example where this could be demonstrated?

Hmm, do you think the two examples in the initial email of this thread
can serve the purpose, by observing how we avoid building access paths
for the dummy rel with this optimization?

Thanks
Richard

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