Refactor ALTER some-obj RENAME implementation

Remove duplicate implementations of catalog munging and miscellaneous
privilege checks.  Instead rely on already existing data in
objectaddress.c to do the work.

Author: KaiGai Kohei, changes by me
Reviewed by: Robert Haas, Álvaro Herrera, Dimitri Fontaine

Author: alvherre

src/backend/catalog/objectaddress.c

@@ -80,7 +80,9 @@ typedef struct
 	Oid			class_oid;		/* oid of catalog */
 	Oid			oid_index_oid;	/* oid of index on system oid column */
 	int			oid_catcache_id;	/* id of catcache on system oid column	*/
-	int			name_catcache_id;		/* id of catcache on (name,namespace) */
+	int			name_catcache_id;		/* id of catcache on (name,namespace),
+										 * or (name) if the object does not
+										 * live in a namespace */
 	AttrNumber	attnum_name;	/* attnum of name field */
 	AttrNumber	attnum_namespace;		/* attnum of namespace field */
 	AttrNumber	attnum_owner;	/* attnum of owner field */

src/backend/commands/aggregatecmds.c

@@ -226,66 +226,3 @@ DefineAggregate(List *name, List *args, bool oldstyle, List *parameters)
 						   transTypeId,	/* transition data type */
 						   initval);	/* initial condition */
 }
-
-
-/*
- * RenameAggregate
- *		Rename an aggregate.
- */
-Oid
-RenameAggregate(List *name, List *args, const char *newname)
-{
-	Oid			procOid;
-	Oid			namespaceOid;
-	HeapTuple	tup;
-	Form_pg_proc procForm;
-	Relation	rel;
-	AclResult	aclresult;
-
-	rel = heap_open(ProcedureRelationId, RowExclusiveLock);
-
-	/* Look up function and make sure it's an aggregate */
-	procOid = LookupAggNameTypeNames(name, args, false);
-
-	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(procOid));
-	if (!HeapTupleIsValid(tup)) /* should not happen */
-		elog(ERROR, "cache lookup failed for function %u", procOid);
-	procForm = (Form_pg_proc) GETSTRUCT(tup);
-
-	namespaceOid = procForm->pronamespace;
-
-	/* make sure the new name doesn't exist */
-	if (SearchSysCacheExists3(PROCNAMEARGSNSP,
-							  CStringGetDatum(newname),
-							  PointerGetDatum(&procForm->proargtypes),
-							  ObjectIdGetDatum(namespaceOid)))
-		ereport(ERROR,
-				(errcode(ERRCODE_DUPLICATE_FUNCTION),
-				 errmsg("function %s already exists in schema \"%s\"",
-						funcname_signature_string(newname,
-												  procForm->pronargs,
-												  NIL,
-											   procForm->proargtypes.values),
-						get_namespace_name(namespaceOid))));
-
-	/* must be owner */
-	if (!pg_proc_ownercheck(procOid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC,
-					   NameListToString(name));
-
-	/* must have CREATE privilege on namespace */
-	aclresult = pg_namespace_aclcheck(namespaceOid, GetUserId(), ACL_CREATE);
-	if (aclresult != ACLCHECK_OK)
-		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
-					   get_namespace_name(namespaceOid));
-
-	/* rename */
-	namestrcpy(&(((Form_pg_proc) GETSTRUCT(tup))->proname), newname);
-	simple_heap_update(rel, &tup->t_self, tup);
-	CatalogUpdateIndexes(rel, tup);
-
-	heap_close(rel, NoLock);
-	heap_freetuple(tup);
-
-	return procOid;
-}