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From: Michael Paquier <michael@paquier.xyz>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Initialize read stream before fetching metapage in hash bulk-del
Date: Wed, 05 Aug 2026 07:57:17 +0000
Message-ID: <E1wrWV3-00000000Gyv-12x4@gemulon.postgresql.org> (raw)

Initialize read stream before fetching metapage in hash bulk-deletion

hashbulkdelete() fetched the relcache's cached hash metapage before
calling read_stream_begin_relation().  During the read stream
initialization, relation lookups may process pending relcache
invalidation messages, which could cause the cached metapage to be
invalidated before the read stream uses it, leading to the failure of a
VACUUM bulk-deletion for a hash index.

This commit reworks the order of hashbulkdelete() so as its read stream
is initialized before fetching the cached metapage, so as pending
invalidation messages do not interfere with the relation scan.

Issue introduced by bfa3c4f106b1.

Author: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
Discussion: https://postgr.es/m/CADzfLwVEJ2_7ioX3ZSB1P7qXW40ghUy_ZCzeFvhDLoa_3Muztg@mail.gmail.com
Backpatch-through: 19

Branch
------
REL_19_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/0e2fb2c8c307aaee5ab47aa92055b53ca146706b

Modified Files
--------------
src/backend/access/hash/hash.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)



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