From: Richard Guo <rguo@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Avoid creating duplicate ordered append paths
Date: Wed, 05 Nov 2025 09:13:16 +0000
Message-ID: <E1vGZZs-00583Q-1m@gemulon.postgresql.org> (raw)
Avoid creating duplicate ordered append paths
In generate_orderedappend_paths(), the function does not handle the
case where the paths in total_subpaths and fractional_subpaths are
identical. This situation is not uncommon, and as a result, it may
generate two exactly identical ordered append paths.
Fix by checking whether total_subpaths and fractional_subpaths contain
the same paths, and skipping creation of the ordered append path for
the fractional case when they are identical.
Given the lack of field complaints about this, I'm a bit hesitant to
back-patch, but let's clean it up in HEAD.
Author: Richard Guo <guofenglinux@gmail.com>
Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Discussion: https://postgr.es/m/CAMbWs4-OYsgA75tGGiBARt87G0y_z_GBTSLrzudcJxAzndYkYw@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/0ea5eee37606386150aa8317184617e1d5d34565
Modified Files
--------------
src/backend/optimizer/path/allpaths.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: rguo@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Avoid creating duplicate ordered append paths
In-Reply-To: <E1vGZZs-00583Q-1m@gemulon.postgresql.org>
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