From e468ec0fddcd93e282da6685b75d5687c2a87f2a Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Fri, 15 Nov 2024 08:42:59 +0100
Subject: [PATCH] Add an assertion in get_object_address()

Some places declared a Relation before calling get_object_address()
only to assert that the relation is NULL after the call.

The new assertion allows passing NULL as the relation argument at
those places making the code cleaner and easier to understand.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://www.postgresql.org/message-id/ZzG34eNrT83W/Orz@ip-10-97-1-34.eu-west-3.compute.internal
---
 src/backend/catalog/objectaddress.c |  9 +++++++--
 src/backend/commands/alter.c        | 15 ++++-----------
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index 85a7b7e641..7520a98215 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -896,7 +896,8 @@ static void getRelationIdentity(StringInfo buffer, Oid relid, List **object,
  *
  * If the object is a relation or a child object of a relation (e.g. an
  * attribute or constraint), the relation is also opened and *relp receives
- * the open relcache entry pointer; otherwise, *relp is set to NULL.  This
+ * the open relcache entry pointer; otherwise, *relp is set to NULL.
+ * (relp can be NULL if the caller never passes a relation-related object.)  This
  * is a bit grotty but it makes life simpler, since the caller will
  * typically need the relcache entry too.  Caller must close the relcache
  * entry when done with it.  The relation is locked with the specified lockmode
@@ -1204,8 +1205,12 @@ get_object_address(ObjectType objtype, Node *object,
 		old_address = address;
 	}
 
+	/* relp must be given if it's a relation */
+	Assert(!relation || relp);
+
 	/* Return the object address and the relation. */
-	*relp = relation;
+	if (relp)
+		*relp = relation;
 	return address;
 }
 
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index 4f99ebb447..a45f3bb6b8 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -421,13 +421,11 @@ ExecRenameStmt(RenameStmt *stmt)
 			{
 				ObjectAddress address;
 				Relation	catalog;
-				Relation	relation;
 
 				address = get_object_address(stmt->renameType,
 											 stmt->object,
-											 &relation,
+											 NULL,
 											 AccessExclusiveLock, false);
-				Assert(relation == NULL);
 
 				catalog = table_open(address.classId, RowExclusiveLock);
 				AlterObjectRename_internal(catalog,
@@ -482,8 +480,7 @@ ExecAlterObjectDependsStmt(AlterObjectDependsStmt *stmt, ObjectAddress *refAddre
 		table_close(rel, NoLock);
 
 	refAddr = get_object_address(OBJECT_EXTENSION, (Node *) stmt->extname,
-								 &rel, AccessExclusiveLock, false);
-	Assert(rel == NULL);
+								 NULL, AccessExclusiveLock, false);
 	if (refAddress)
 		*refAddress = refAddr;
 
@@ -563,16 +560,14 @@ ExecAlterObjectSchemaStmt(AlterObjectSchemaStmt *stmt,
 		case OBJECT_TSTEMPLATE:
 			{
 				Relation	catalog;
-				Relation	relation;
 				Oid			classId;
 				Oid			nspOid;
 
 				address = get_object_address(stmt->objectType,
 											 stmt->object,
-											 &relation,
+											 NULL,
 											 AccessExclusiveLock,
 											 false);
-				Assert(relation == NULL);
 				classId = address.classId;
 				catalog = table_open(classId, RowExclusiveLock);
 				nspOid = LookupCreationNamespace(stmt->newschema);
@@ -876,15 +871,13 @@ ExecAlterOwnerStmt(AlterOwnerStmt *stmt)
 		case OBJECT_TSDICTIONARY:
 		case OBJECT_TSCONFIGURATION:
 			{
-				Relation	relation;
 				ObjectAddress address;
 
 				address = get_object_address(stmt->objectType,
 											 stmt->object,
-											 &relation,
+											 NULL,
 											 AccessExclusiveLock,
 											 false);
-				Assert(relation == NULL);
 
 				AlterObjectOwner_internal(address.classId, address.objectId,
 										  newowner);