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help / color / mirror / Atom feedFrom: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix LIKE/regex optimization for indexscan with exact-match patte
Date: Mon, 06 Jul 2026 17:06:45 +0000
Message-ID: <E1wgmmL-001cNn-19@gemulon.postgresql.org> (raw)
Fix LIKE/regex optimization for indexscan with exact-match pattern.
Commit 85b7efa1c introduced support for LIKE with non-deterministic
collations. By moving some conditionals around, it accidentally broke
the optimization for converting a LIKE or regex exact-match pattern
to an equality indexqual when the index collation doesn't match the
expression collation. That should be allowed if the expression
collation is deterministic. This patch re-introduces the optimization
for that common case.
One important beneficiary of this optimization is the "\d tablename"
command in psql. Without this fix that will do a seqscan on pg_class
instead of an index point lookup.
Reported-by: Andres Freund <andres@anarazel.de>
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/DHBQIZX8SZVI.ZX614ZMFL645@jeltef.nl
Backpatch-through: 18
Branch
------
REL_18_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/d0bb49e61168953f0f07c3beeb2b8fb63a3521a2
Modified Files
--------------
src/backend/utils/adt/like_support.c | 20 ++++++++++++++++----
src/test/regress/expected/collate.icu.utf8.out | 23 +++++++++++++++++++++++
src/test/regress/expected/collate.out | 23 +++++++++++++++++++++++
src/test/regress/sql/collate.icu.utf8.sql | 10 ++++++++++
src/test/regress/sql/collate.sql | 10 ++++++++++
5 files changed, 82 insertions(+), 4 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix LIKE/regex optimization for indexscan with exact-match patte
In-Reply-To: <E1wgmmL-001cNn-19@gemulon.postgresql.org>
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