Horton

Re: Missing docs for new enable_group_by_reordering GUC

Pavel Borisov <pashkin.elfe@gmail.com>

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From: Pavel Borisov <pashkin.elfe@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Andrei Lepikhov <lepihov@gmail.com>, Bruce Momjian <bruce@momjian.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-06-19T15:02:19Z
Lists: pgsql-hackers

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  1. Add doc entry for the new GUC paramenter enable_group_by_reordering

  2. Explore alternative orderings of group-by pathkeys during optimization.

Hi, Alexander!

On Wed, 19 Jun 2024 at 05:27, Alexander Korotkov <aekorotkov@gmail.com>
wrote:

> On Tue, Jun 18, 2024 at 4:14 PM Pavel Borisov <pashkin.elfe@gmail.com>
> wrote:
> >> Controls if the query planner will produce a plan which will provide
> <literal>GROUP BY</literal> keys presorted in the order of keys of a child
> node of the plan, such as an index scan. When disabled, the query planner
> will produce a plan with <literal>GROUP BY</literal> keys only reordered to
> match
> >> the <literal>ORDER BY</literal> clause, if any. When enabled, the
> planner will try to produce a more efficient plan. The default value is on.
> > A correction of myself: presorted -> sorted, reordered ->sorted
>
> Thank you for your review.  I think all of this make sense.  Please,
> check the revised patch attached.
>
To me patch v3 looks good.

Regards,
Pavel Borisov
Supabase