Horton

Re: fix cost subqueryscan wrong parallel cost

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, "David G. Johnston" <david.g.johnston@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-04-29T14:54:16Z
Lists: pgsql-hackers 
I wrote:
> Really?  Maybe I misunderstand the case under consideration, but
> what I think will be happening is that each worker will re-execute
> the pushed-down subquery in full.

Oh ... nevermind that: what I was thinking about was the SubLink/SubPlan
case, which is unrelated to SubqueryScan.  -ENOCAFFEINE, sorry about that.

			regards, tom lane

Commits

  1. Fix rowcount estimate for SubqueryScan that's under a Gather.

  2. Optimize order of GROUP BY keys