v27-0001-Use-version-for-builtin-collations.patch

From 98d894e141cbf0701714efad3afdbc98516b878f Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Thu, 14 Mar 2024 12:07:45 -0700
Subject: [PATCH v27 1/5] Use version for builtin collations.

------ CATVERSION ------

Even though we don't expect any changes to memcmp() semantics, it's
plausible that the surrounding optimizations (including future
optimizations that don't exist today) may have bugs.

Given that the version field already exists, there's little reason not
to use it. Suggestion from Peter Eisentraut.

Discussion: https://postgr.es/m/613c120a-5413-4fa7-a501-6590eae558f8@eisentraut.org
---
 src/backend/utils/adt/pg_locale.c    | 15 +++++++++++++--
 src/include/catalog/pg_collation.dat |  4 ++--
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index e10d328fc3..aa40921d7d 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1732,13 +1732,24 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 
 	/*
 	 * The only two supported locales (C and C.UTF-8) are both based on memcmp
-	 * and are not expected to change.
+	 * and are not expected to change, but track the version anyway.
 	 *
 	 * Note that the character semantics may change for some locales, but the
 	 * collation version only tracks changes to sort order.
 	 */
 	if (collprovider == COLLPROVIDER_BUILTIN)
-		return NULL;
+	{
+		Assert(collcollate != NULL);
+		if (strcmp(collcollate, "C") == 0)
+			return "1";
+		else if (strcmp(collcollate, "C.UTF-8") == 0)
+			return "1";
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					 errmsg("invalid locale name \"%s\" for builtin provider",
+							collcollate)));
+	}
 
 #ifdef USE_ICU
 	if (collprovider == COLLPROVIDER_ICU)
diff --git a/src/include/catalog/pg_collation.dat b/src/include/catalog/pg_collation.dat
index 083b0cdcca..dcf554bbd5 100644
--- a/src/include/catalog/pg_collation.dat
+++ b/src/include/catalog/pg_collation.dat
@@ -25,13 +25,13 @@
   collcollate => 'POSIX', collctype => 'POSIX' },
 { oid => '962', descr => 'sorts by Unicode code point, C character semantics',
   collname => 'ucs_basic', collprovider => 'b', collencoding => '6',
-  colllocale => 'C' },
+  colllocale => 'C', collversion => '1' },
 { oid => '963',
   descr => 'sorts using the Unicode Collation Algorithm with default settings',
   collname => 'unicode', collprovider => 'i', collencoding => '-1',
   colllocale => 'und' },
 { oid => '811', descr => 'sorts by Unicode code point; Unicode and POSIX character semantics',
   collname => 'pg_c_utf8', collprovider => 'b', collencoding => '6',
-  colllocale => 'C.UTF-8' },
+  colllocale => 'C.UTF-8', collversion => '1' },
 
 ]
-- 
2.34.1