From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: Sanyo Moura <sanyo.moura@tatic.net>
Cc: jeff.janes@gmail.com, David Rowley <david.rowley@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: pgsql-performance@lists.postgresql.org, Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Query with high planning time at version 11.1 compared versions 10.5 and 11.0
Date: Thu, 6 Dec 2018 04:57:26 -0300
Message-ID: <20181206075726.pig32e6thltb56hr@alvherre.pgsql> (raw)
In-Reply-To: <8db4eca8-6e76-70ff-f934-e0228a1cc298@lab.ntt.co.jp>
On 2018-Dec-06, Amit Langote wrote:
> The partitionwise join related
> changes in PG 11 moved the add_child_rel_equivalences call in
> set_append_rel_size such that child EC members would be added even before
> checking if the child rel is dummy, but for a reason named in the comment
> above the call:
>
> ... Even if this child is
> * deemed dummy, it may fall on nullable side in a child-join, which
> * in turn may participate in a MergeAppend, where we will need the
> * EquivalenceClass data structures.
>
> However, I think we can skip adding the dummy child EC members here and
> instead make it a responsibility of partitionwise join code in joinrels.c
> to add the needed EC members. Attached a patch to show what I mean, which
> passes the tests and gives this planning time:
Robert, Ashutosh, any comments on this? I'm unfamiliar with the
partitionwise join code.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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Subject: Re: Query with high planning time at version 11.1 compared versions 10.5 and 11.0
In-Reply-To: <20181206075726.pig32e6thltb56hr@alvherre.pgsql>
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