From: Michael Paquier <michael@paquier.xyz>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix unexpected reversal of lists during catcache rehash
Date: Wed, 07 Jan 2026 08:53:17 +0000
Message-ID: <E1vdPI4-0054B5-12@gemulon.postgresql.org> (raw)
Fix unexpected reversal of lists during catcache rehash
During catcache searches, the most-recently searched entries are kept at
the head of the list to speed up subsequent searches, keeping the
"freshest" entries at its beginning. A rehash of the catcache was doing
the opposite: fresh entries were moved to the tail of the newly-created
buckets, causing a rehash to slow down a bit.
When a rehash is done, this commit switches the code to use
dlist_push_tail() instead of dlist_push_head(), so as fresh entries are
kept at the head of the lists, not their tail.
Author: ChangAo Chen <cca5507@qq.com>
Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/tencent_9EA10D8512B5FE29E7323F780A0749768708@qq.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/68119480a763d761a9cf2413f4320d9a5d4b34d5
Modified Files
--------------
src/backend/utils/cache/catcache.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: michael@paquier.xyz, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix unexpected reversal of lists during catcache rehash
In-Reply-To: <E1vdPI4-0054B5-12@gemulon.postgresql.org>
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