Re: Performance regression with PostgreSQL 11 and partitioning

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Amit Langote <amitlangote09(at)gmail(dot)com>
Cc: Thomas Reiss <thomas(dot)reiss(at)dalibo(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Performance regression with PostgreSQL 11 and partitioning
Date: 2018-05-25 19:05:42
Message-ID: CA+TgmoZwbR-2fc_71nZ82si5K=mbV+7PpRsqy9cP2LBj-TNtBQ@mail.gmail.com
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On Fri, May 25, 2018 at 1:53 PM, Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> Seems here that we call find_appinfos_by_relids here for *all*
> partitions, even if all but one partition may have been pruned. I
> haven't studied this code in detail, but I suspect it might be
> unnecessary, although I might be wrong.

Uggh. It might be possible to skip it for dummy children. That would
leave the dummy child rels generating a different pathtarget than the
non-dummy children, but I guess if we never use them again maybe it
wouldn't matter.

> Fwiw, I'm not sure why the new pruning code would call here, at least
> git grep find_appinfos_by_relids doesn't turn up anything interesting
> in that regard.

Hmm, OK.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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