From: Jeff Davis <jdavis@postgresql.org>
Date: Wed, 6 Nov 2024 22:44:35 +0000 (-0800)
Subject: Fix lc_collate_is_c() when LC_COLLATE != LC_CTYPE.
X-Git-Tag: REL_17_1~18
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8148e7124d550770e3a9064b9b45b354d783b949;p=thirdparty%2Fpostgresql.git

Fix lc_collate_is_c() when LC_COLLATE != LC_CTYPE.

An unfortunate typo in commit 2d819a08a1 can cause wrong results when
the default collation provider is libc, LC_CTYPE=C, and LC_COLLATE is
a real locale. Users with this combination of settings must REINDEX
all affected indexes.

The same typo can also cause performance degradation when LC_COLLATE=C
and LC_CTYPE is a real locale.

Problem does not exist in master (due to refactoring), so fix only in
version 17.

Reported-by: Drew Callahan
Discussion: https://postgr.es/m/d5081a7f4f6d425c28dd69d1e09b2e78f149e726.camel@j-davis.com
---

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index cd5ad1e7056..4c85a01b284 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1370,9 +1370,9 @@ lc_collate_is_c(Oid collation)
 		}
 		else if (default_locale.provider == COLLPROVIDER_LIBC)
 		{
-			localeptr = setlocale(LC_CTYPE, NULL);
+			localeptr = setlocale(LC_COLLATE, NULL);
 			if (!localeptr)
-				elog(ERROR, "invalid LC_CTYPE setting");
+				elog(ERROR, "invalid LC_COLLATE setting");
 		}
 		else
 			elog(ERROR, "unexpected collation provider '%c'",