From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix LIKE matching with nondeterministic collations and backslash
Date: Mon, 06 Jul 2026 18:48:15 +0000
Message-ID: <E1wgoMZ-001d4S-1V@gemulon.postgresql.org> (raw)
Fix LIKE matching with nondeterministic collations and backslashes.
Commit 85b7efa1c added support for LIKE with nondeterministic
collations, but it included a bug in the de-escaping logic for
literal pattern substrings. That unconditionally skipped all
backslashes, but when it encounters '\\' it should emit the second
backslash as a de-escaped character. That led to acting as though
the escaped backslash was not there.
Bug: #19474
Reported-by: Bowen Shi <zxwsbg12138@gmail.com>
Author: Nitin Motiani <nitinmotiani@google.com>
Reviewed-by: Zsolt Parragi <zsolt.parragi@percona.com>
Reviewed-by: Ewan Young <kdbase.hack@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19474-5b86a95f3d9a7ecb@postgresql.org
Discussion: https://postgr.es/m/CAH5HC94yU+K8Gcdy12M5BS8gwD_SXLSHzc9k5tNk7JDnpBiFMA@mail.gmail.com
Backpatch-through: 18
Branch
------
REL_19_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/99775b3885b600277dea577db69e7469e59bcdbe
Modified Files
--------------
src/backend/utils/adt/like_match.c | 5 ++---
src/test/regress/expected/collate.icu.utf8.out | 31 ++++++++++++++++++++++++++
src/test/regress/sql/collate.icu.utf8.sql | 7 ++++++
3 files changed, 40 insertions(+), 3 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 matching with nondeterministic collations and backslash
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