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

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2023-10-10T05:45:31Z
Lists: pgsql-hackers
On Tue, Oct 10, 2023 at 11:09 AM Richard Guo <guofenglinux@gmail.com> wrote:
> Do you mean the const-folding?  It happens in the preprocessing phase,
> specifically in eval_const_expressions().

Thanks.

> 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?

-- 
Best Wishes,
Ashutosh Bapat



Commits

  1. Fix missed optimization in relation_excluded_by_constraints().