Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0

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От Alvaro Herrera
Тема Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0
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Msg-id 20181206075726.pig32e6thltb56hr@alvherre.pgsql
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Ответ на Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0  (Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>)
Ответы Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0  (Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>)
Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0  (Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>)
Список pgsql-performance
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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