0001-Improve-error-message-for-pg_collation_actual_versio.patch

From 992608eb81265856af3b9cbcb63597d91876090a Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 17 Feb 2021 14:10:40 +1300
Subject: [PATCH 1/4] Improve error message for pg_collation_actual_version().

Instead of an internal "cache lookup failed" message, show a message
intended for end user consumption, considering this is a user-exposed
function.

Reported-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20210117215940.GE8560%40telsasoft.com
---
 src/backend/catalog/index.c          |  5 +++--
 src/backend/catalog/pg_depend.c      |  3 ++-
 src/backend/commands/collationcmds.c |  8 +++++++-
 src/backend/utils/adt/pg_locale.c    | 17 +++++++++++++++--
 src/include/utils/pg_locale.h        |  2 +-
 5 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1514937748..1c808f55c5 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1290,7 +1290,8 @@ do_collation_version_check(const ObjectAddress *otherObject,
 		return false;
 
 	/* Ask the provider for the current version.  Give up if unsupported. */
-	current_version = get_collation_version_for_oid(otherObject->objectId);
+	current_version = get_collation_version_for_oid(otherObject->objectId,
+													NULL);
 	if (!current_version)
 		return false;
 
@@ -1369,7 +1370,7 @@ do_collation_version_update(const ObjectAddress *otherObject,
 	if (OidIsValid(*coll) && otherObject->objectId != *coll)
 		return false;
 
-	*new_version = get_collation_version_for_oid(otherObject->objectId);
+	*new_version = get_collation_version_for_oid(otherObject->objectId, NULL);
 
 	return true;
 }
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 63da24322d..aee59eef39 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -116,7 +116,8 @@ recordMultipleDependencies(const ObjectAddress *depender,
 					referenced->objectId == POSIX_COLLATION_OID)
 					continue;
 
-				version = get_collation_version_for_oid(referenced->objectId);
+				version = get_collation_version_for_oid(referenced->objectId,
+														NULL);
 
 				/*
 				 * Default collation is pinned, so we need to force recording
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index 9634ae6809..b3c59e6e9f 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -272,8 +272,14 @@ pg_collation_actual_version(PG_FUNCTION_ARGS)
 {
 	Oid			collid = PG_GETARG_OID(0);
 	char	   *version;
+	bool		found;
 
-	version = get_collation_version_for_oid(collid);
+	version = get_collation_version_for_oid(collid, &found);
+
+	if (!found)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("no collation found for OID %u", collid)));
 
 	if (version)
 		PG_RETURN_TEXT_P(cstring_to_text(version));
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index e9c1231f9b..3cd9257800 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1726,10 +1726,12 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 /*
  * Get provider-specific collation version string for a given collation OID.
  * Return NULL if the provider doesn't support versions, or the collation is
- * unversioned (for example "C").
+ * unversioned (for example "C").  If "found" is non-NULL, unknown OIDs are
+ * reported through this output parameter; otherwise, an internal error is
+ * raised for unknown OIDs.
  */
 char *
-get_collation_version_for_oid(Oid oid)
+get_collation_version_for_oid(Oid oid, bool *found)
 {
 	HeapTuple	tp;
 	char	   *version;
@@ -1744,6 +1746,8 @@ get_collation_version_for_oid(Oid oid)
 		dbform = (Form_pg_database) GETSTRUCT(tp);
 		version = get_collation_actual_version(COLLPROVIDER_LIBC,
 											   NameStr(dbform->datcollate));
+		if (found)
+			*found = true;
 	}
 	else
 	{
@@ -1751,10 +1755,19 @@ get_collation_version_for_oid(Oid oid)
 
 		tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(oid));
 		if (!HeapTupleIsValid(tp))
+		{
+			if (found)
+			{
+				*found = false;
+				return NULL;
+			}
 			elog(ERROR, "cache lookup failed for collation %u", oid);
+		}
 		collform = (Form_pg_collation) GETSTRUCT(tp);
 		version = get_collation_actual_version(collform->collprovider,
 											   NameStr(collform->collcollate));
+		if (found)
+			*found = true;
 	}
 
 	ReleaseSysCache(tp);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 34dff74bd1..9d73774a19 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -103,7 +103,7 @@ typedef struct pg_locale_struct *pg_locale_t;
 
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
-extern char *get_collation_version_for_oid(Oid collid);
+extern char *get_collation_version_for_oid(Oid collid, bool *found);
 
 #ifdef USE_ICU
 extern int32_t icu_to_uchar(UChar **buff_uchar, const char *buff, size_t nbytes);
-- 
2.30.0