Improve behavior of concurrent rename statements.

Previously, renaming a table, sequence, view, index, foreign table,
column, or trigger checked permissions before locking the object, which
meant that if permissions were revoked during the lock wait, we would
still allow the operation.  Similarly, if the original object is dropped
and a new one with the same name is created, the operation will be allowed
if we had permissions on the old object; the permissions on the new
object don't matter.  All this is now fixed.

Along the way, attempting to rename a trigger on a foreign table now gives
the same error message as trying to create one there in the first place
(i.e. that it's not a table or view) rather than simply stating that no
trigger by that name exists.

Patch by me; review by Noah Misch.

src/backend/commands/alter.c

@@ -101,66 +101,22 @@ ExecRenameStmt(RenameStmt *stmt)
 			RenameTableSpace(stmt->subname, stmt->newname);
 			break;
 
-		case OBJECT_TABLE:
-		case OBJECT_SEQUENCE:
-		case OBJECT_VIEW:
-		case OBJECT_INDEX:
-		case OBJECT_COLUMN:
-		case OBJECT_ATTRIBUTE:
-		case OBJECT_TRIGGER:
-		case OBJECT_FOREIGN_TABLE:
-			{
-				Oid			relid;
-
-				CheckRelationOwnership(stmt->relation, true);
-
-				/*
-				 * Lock level used here should match what will be taken later,
-				 * in RenameRelation, renameatt, or renametrig.
-				 */
-				relid = RangeVarGetRelid(stmt->relation, AccessExclusiveLock,
-										 false);
-
-				switch (stmt->renameType)
-				{
 		case OBJECT_TABLE:
 		case OBJECT_SEQUENCE:
 		case OBJECT_VIEW:
 		case OBJECT_INDEX:
 		case OBJECT_FOREIGN_TABLE:
-						{
-							/*
-							 * RENAME TABLE requires that we (still) hold
-							 * CREATE rights on the containing namespace, as
-							 * well as ownership of the table.
-							 */
-							Oid			namespaceId = get_rel_namespace(relid);
-							AclResult	aclresult;
-
-							aclresult = pg_namespace_aclcheck(namespaceId,
-															  GetUserId(),
-															  ACL_CREATE);
-							if (aclresult != ACLCHECK_OK)
-								aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
-											get_namespace_name(namespaceId));
-
-							RenameRelation(relid, stmt->newname, stmt->renameType);
+			RenameRelation(stmt);
 			break;
-						}
+
 		case OBJECT_COLUMN:
 		case OBJECT_ATTRIBUTE:
-						renameatt(relid, stmt);
+			renameatt(stmt);
 			break;
+
 		case OBJECT_TRIGGER:
-						renametrig(relid,
-								   stmt->subname,		/* old att name */
-								   stmt->newname);		/* new att name */
+			renametrig(stmt);
 			break;
-					default:
-						 /* can't happen */ ;
-				}
-				break;
-			}
 
 		case OBJECT_TSPARSER:
 			RenameTSParser(stmt->object, stmt->newname);

src/backend/commands/cluster.c

@@ -1474,28 +1474,24 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 		{
 			Relation	toastrel;
 			Oid			toastidx;
-			Oid			toastnamespace;
 			char		NewToastName[NAMEDATALEN];
 
 			toastrel = relation_open(newrel->rd_rel->reltoastrelid,
 									 AccessShareLock);
 			toastidx = toastrel->rd_rel->reltoastidxid;
-			toastnamespace = toastrel->rd_rel->relnamespace;
 			relation_close(toastrel, AccessShareLock);
 
 			/* rename the toast table ... */
 			snprintf(NewToastName, NAMEDATALEN, "pg_toast_%u",
 					 OIDOldHeap);
 			RenameRelationInternal(newrel->rd_rel->reltoastrelid,
-								   NewToastName,
-								   toastnamespace);
+								   NewToastName);
 
 			/* ... and its index too */
 			snprintf(NewToastName, NAMEDATALEN, "pg_toast_%u_index",
 					 OIDOldHeap);
 			RenameRelationInternal(toastidx,
-								   NewToastName,
-								   toastnamespace);
+								   NewToastName);
 		}
 		relation_close(newrel, NoLock);
 	}

src/backend/commands/tablecmds.c

@@ -2064,33 +2064,15 @@ SetRelationHasSubclass(Oid relationId, bool relhassubclass)
 	heap_close(relationRelation, RowExclusiveLock);
 }
 
-
 /*
- *		renameatt_internal		- workhorse for renameatt
+ *		renameatt_check			- basic sanity checks before attribute rename
  */
 static void
-renameatt_internal(Oid myrelid,
-				   const char *oldattname,
-				   const char *newattname,
-				   bool recurse,
-				   bool recursing,
-				   int expected_parents,
-				   DropBehavior behavior)
+renameatt_check(Oid myrelid, Form_pg_class classform, bool recursing)
 {
-	Relation	targetrelation;
-	Relation	attrelation;
-	HeapTuple	atttup;
-	Form_pg_attribute attform;
-	int			attnum;
-	char		relkind;
+	char		relkind = classform->relkind;
 
-	/*
-	 * Grab an exclusive lock on the target table, which we will NOT release
-	 * until end of transaction.
-	 */
-	targetrelation = relation_open(myrelid, AccessExclusiveLock);
-
-	if (targetrelation->rd_rel->reloftype && !recursing)
+	if (classform->reloftype && !recursing)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("cannot rename column of typed table")));
@@ -2102,7 +2084,6 @@ renameatt_internal(Oid myrelid,
 	 * change names that are hardcoded into the system, hence the following
 	 * restriction.
 	 */
-	relkind = RelationGetForm(targetrelation)->relkind;
 	if (relkind != RELKIND_RELATION &&
 		relkind != RELKIND_VIEW &&
 		relkind != RELKIND_COMPOSITE_TYPE &&
@@ -2111,19 +2092,45 @@ renameatt_internal(Oid myrelid,
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("\"%s\" is not a table, view, composite type, index or foreign table",
-						RelationGetRelationName(targetrelation))));
+						NameStr(classform->relname))));
 
 	/*
 	 * permissions checking.  only the owner of a class can change its schema.
 	 */
 	if (!pg_class_ownercheck(myrelid, GetUserId()))
 		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
-					   RelationGetRelationName(targetrelation));
-	if (!allowSystemTableMods && IsSystemRelation(targetrelation))
+					   NameStr(classform->relname));
+	if (!allowSystemTableMods && IsSystemClass(classform))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 				 errmsg("permission denied: \"%s\" is a system catalog",
-						RelationGetRelationName(targetrelation))));
+						NameStr(classform->relname))));
+}
+
+/*
+ *		renameatt_internal		- workhorse for renameatt
+ */
+static void
+renameatt_internal(Oid myrelid,
+				   const char *oldattname,
+				   const char *newattname,
+				   bool recurse,
+				   bool recursing,
+				   int expected_parents,
+				   DropBehavior behavior)
+{
+	Relation	targetrelation;
+	Relation	attrelation;
+	HeapTuple	atttup;
+	Form_pg_attribute attform;
+	int			attnum;
+
+	/*
+	 * Grab an exclusive lock on the target table, which we will NOT release
+	 * until end of transaction.
+	 */
+	targetrelation = relation_open(myrelid, AccessExclusiveLock);
+	renameatt_check(myrelid, RelationGetForm(targetrelation), recursing);
 
 	/*
 	 * if the 'recurse' flag is set then we are supposed to rename this
@@ -2252,14 +2259,38 @@ renameatt_internal(Oid myrelid,
 	relation_close(targetrelation, NoLock);		/* close rel but keep lock */
 }
 
+/*
+ * Perform permissions and integrity checks before acquiring a relation lock.
+ */
+static void
+RangeVarCallbackForRenameAttribute(const RangeVar *rv, Oid relid, Oid oldrelid,
+								   void *arg)
+{
+	HeapTuple		tuple;
+	Form_pg_class	form;
+
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		return;							/* concurrently dropped */
+	form = (Form_pg_class) GETSTRUCT(tuple);
+	renameatt_check(relid, form, false);
+	ReleaseSysCache(tuple);
+}
 
 /*
  *		renameatt		- changes the name of a attribute in a relation
  */
 void
-renameatt(Oid myrelid, RenameStmt *stmt)
+renameatt(RenameStmt *stmt)
 {
-	renameatt_internal(myrelid,
+	Oid			relid;
+
+	/* lock level taken here should match renameatt_internal */
+	relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
+									 false, false,
+									 RangeVarCallbackForRenameAttribute,
+									 NULL);
+	renameatt_internal(relid,
 					   stmt->subname,	/* old att name */
 					   stmt->newname,	/* new att name */
 					   interpretInhOption(stmt->relation->inhOpt),		/* recursive? */
@@ -2268,29 +2299,44 @@ renameatt(Oid myrelid, RenameStmt *stmt)
 					   stmt->behavior);
 }
 
-
 /*
- * Execute ALTER TABLE/INDEX/SEQUENCE/VIEW/FOREIGN TABLE RENAME
- *
- * Caller has already done permissions checks.
+ * Perform permissions and integrity checks before acquiring a relation lock.
  */
-void
-RenameRelation(Oid myrelid, const char *newrelname, ObjectType reltype)
+static void
+RangeVarCallbackForRenameRelation(const RangeVar *rv, Oid relid, Oid oldrelid,
+								  void *arg)
 {
-	Relation	targetrelation;
-	Oid			namespaceId;
+	RenameStmt	   *stmt = (RenameStmt *) arg;
+	ObjectType		reltype;
+	HeapTuple		tuple;
+	Form_pg_class	classform;
+	AclResult   	aclresult;
 	char			relkind;
 
-	/*
-	 * Grab an exclusive lock on the target table, index, sequence or view,
-	 * which we will NOT release until end of transaction.
-	 *
-	 * Lock level used here should match ExecRenameStmt
-	 */
-	targetrelation = relation_open(myrelid, AccessExclusiveLock);
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		return;							/* concurrently dropped */
+	classform = (Form_pg_class) GETSTRUCT(tuple);
+	relkind = classform->relkind;
 
-	namespaceId = RelationGetNamespace(targetrelation);
-	relkind = targetrelation->rd_rel->relkind;
+	/* Must own table. */
+	if (!pg_class_ownercheck(relid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
+					   NameStr(classform->relname));
+
+	/* No system table modifications unless explicitly allowed. */
+	if (!allowSystemTableMods && IsSystemClass(classform))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a system catalog",
+						NameStr(classform->relname))));
+
+	/* Must (still) have CREATE rights on containing namespace. */
+ 	aclresult = pg_namespace_aclcheck(classform->relnamespace, GetUserId(),
+									  ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
+					   get_namespace_name(classform->relnamespace));
 
 	/*
 	 * For compatibility with prior releases, we don't complain if ALTER TABLE
@@ -2298,23 +2344,21 @@ RenameRelation(Oid myrelid, const char *newrelname, ObjectType reltype)
 	 * ALTER SEQUENCE/VIEW/FOREIGN TABLE are only to be used with relations of
 	 * that type.
 	 */
+	reltype = stmt->renameType;
 	if (reltype == OBJECT_SEQUENCE && relkind != RELKIND_SEQUENCE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("\"%s\" is not a sequence",
-						RelationGetRelationName(targetrelation))));
+				 errmsg("\"%s\" is not a sequence", rv->relname)));
 
 	if (reltype == OBJECT_VIEW && relkind != RELKIND_VIEW)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("\"%s\" is not a view",
-						RelationGetRelationName(targetrelation))));
+				 errmsg("\"%s\" is not a view", rv->relname)));
 
 	if (reltype == OBJECT_FOREIGN_TABLE && relkind != RELKIND_FOREIGN_TABLE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("\"%s\" is not a foreign table",
-						RelationGetRelationName(targetrelation))));
+				 errmsg("\"%s\" is not a foreign table", rv->relname)));
 
 	/*
 	 * Don't allow ALTER TABLE on composite types. We want people to use ALTER
@@ -2323,17 +2367,35 @@ RenameRelation(Oid myrelid, const char *newrelname, ObjectType reltype)
 	if (relkind == RELKIND_COMPOSITE_TYPE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("\"%s\" is a composite type",
-						RelationGetRelationName(targetrelation)),
+				 errmsg("\"%s\" is a composite type", rv->relname),
 				 errhint("Use ALTER TYPE instead.")));
 
-	/* Do the work */
-	RenameRelationInternal(myrelid, newrelname, namespaceId);
+	ReleaseSysCache(tuple);
+}
+
+
+/*
+ * Execute ALTER TABLE/INDEX/SEQUENCE/VIEW/FOREIGN TABLE RENAME
+ */
+void
+RenameRelation(RenameStmt *stmt)
+{
+	Oid			relid;
 
 	/*
-	 * Close rel, but keep exclusive lock!
+	 * Grab an exclusive lock on the target table, index, sequence or view,
+	 * which we will NOT release until end of transaction.
+	 *
+	 * Lock level used here should match RenameRelationInternal, to avoid
+	 * lock escalation.
 	 */
-	relation_close(targetrelation, NoLock);
+	relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
+									 false, false,
+									 RangeVarCallbackForRenameRelation,
+									 (void *) stmt);
+
+	/* Do the work */
+	RenameRelationInternal(relid, stmt->newname);
 }
 
 /*
@@ -2346,18 +2408,20 @@ RenameRelation(Oid myrelid, const char *newrelname, ObjectType reltype)
  *			  sequence, AFAIK there's no need for it to be there.
  */
 void
-RenameRelationInternal(Oid myrelid, const char *newrelname, Oid namespaceId)
+RenameRelationInternal(Oid myrelid, const char *newrelname)
 {
 	Relation	targetrelation;
 	Relation	relrelation;	/* for RELATION relation */
 	HeapTuple	reltup;
 	Form_pg_class relform;
+	Oid			namespaceId;
 
 	/*
 	 * Grab an exclusive lock on the target table, index, sequence or view,
 	 * which we will NOT release until end of transaction.
 	 */
 	targetrelation = relation_open(myrelid, AccessExclusiveLock);
+	namespaceId = RelationGetNamespace(targetrelation);
 
 	/*
 	 * Find relation's pg_class tuple, and make sure newrelname isn't in use.
@@ -5376,7 +5440,7 @@ ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
 		ereport(NOTICE,
 				(errmsg("ALTER TABLE / ADD CONSTRAINT USING INDEX will rename index \"%s\" to \"%s\"",
 						indexName, constraintName)));
-		RenameRelation(index_oid, constraintName, OBJECT_INDEX);
+		RenameRelationInternal(index_oid, constraintName);
 	}
 
 	/* Extra checks needed if making primary key */

src/backend/commands/trigger.c

@@ -1151,6 +1151,39 @@ get_trigger_oid(Oid relid, const char *trigname, bool missing_ok)
 	return oid;
 }
 
+/*
+ * Perform permissions and integrity checks before acquiring a relation lock.
+ */
+static void
+RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
+								 void *arg)
+{
+    HeapTuple       tuple;
+    Form_pg_class   form;
+
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		return;                         /* concurrently dropped */
+	form = (Form_pg_class) GETSTRUCT(tuple);
+
+	/* only tables and views can have triggers */
+    if (form->relkind != RELKIND_RELATION && form->relkind != RELKIND_VIEW)
+        ereport(ERROR,
+                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+                 errmsg("\"%s\" is not a table or view", rv->relname)));
+
+	/* you must own the table to rename one of its triggers */
+    if (!pg_class_ownercheck(relid, GetUserId()))
+        aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS, rv->relname);
+    if (!allowSystemTableMods && IsSystemClass(form))
+        ereport(ERROR,
+                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+                 errmsg("permission denied: \"%s\" is a system catalog",
+						rv->relname)));
+
+	ReleaseSysCache(tuple);
+}
+
 /*
  *		renametrig		- changes the name of a trigger on a relation
  *
@@ -1165,21 +1198,26 @@ get_trigger_oid(Oid relid, const char *trigname, bool missing_ok)
  *		update row in catalog
  */
 void
-renametrig(Oid relid,
-		   const char *oldname,
-		   const char *newname)
+renametrig(RenameStmt *stmt)
 {
 	Relation	targetrel;
 	Relation	tgrel;
 	HeapTuple	tuple;
 	SysScanDesc tgscan;
 	ScanKeyData key[2];
+	Oid			relid;
 
 	/*
-	 * Grab an exclusive lock on the target table, which we will NOT release
-	 * until end of transaction.
+	 * Look up name, check permissions, and acquire lock (which we will NOT
+	 * release until end of transaction).
 	 */
-	targetrel = heap_open(relid, AccessExclusiveLock);
+	relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
+									 false, false,
+									 RangeVarCallbackForRenameTrigger,
+									 NULL);
+
+	/* Have lock already, so just need to build relcache entry. */
+	targetrel = relation_open(relid, NoLock);
 
 	/*
 	 * Scan pg_trigger twice for existing triggers on relation.  We do this in
@@ -1202,14 +1240,14 @@ renametrig(Oid relid,
 	ScanKeyInit(&key[1],
 				Anum_pg_trigger_tgname,
 				BTEqualStrategyNumber, F_NAMEEQ,
-				PointerGetDatum(newname));
+				PointerGetDatum(stmt->newname));
 	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
 								SnapshotNow, 2, key);
 	if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
 		ereport(ERROR,
 				(errcode(ERRCODE_DUPLICATE_OBJECT),
 				 errmsg("trigger \"%s\" for relation \"%s\" already exists",
-						newname, RelationGetRelationName(targetrel))));
+						stmt->newname, RelationGetRelationName(targetrel))));
 	systable_endscan(tgscan);
 
 	/*
@@ -1222,7 +1260,7 @@ renametrig(Oid relid,
 	ScanKeyInit(&key[1],
 				Anum_pg_trigger_tgname,
 				BTEqualStrategyNumber, F_NAMEEQ,
-				PointerGetDatum(oldname));
+				PointerGetDatum(stmt->subname));
 	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
 								SnapshotNow, 2, key);
 	if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
@@ -1232,7 +1270,8 @@ renametrig(Oid relid,
 		 */
 		tuple = heap_copytuple(tuple);	/* need a modifiable copy */
 
-		namestrcpy(&((Form_pg_trigger) GETSTRUCT(tuple))->tgname, newname);
+		namestrcpy(&((Form_pg_trigger) GETSTRUCT(tuple))->tgname,
+				   stmt->newname);
 
 		simple_heap_update(tgrel, &tuple->t_self, tuple);
 
@@ -1251,7 +1290,7 @@ renametrig(Oid relid,
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("trigger \"%s\" for table \"%s\" does not exist",
-						oldname, RelationGetRelationName(targetrel))));
+						stmt->subname, RelationGetRelationName(targetrel))));
 	}
 
 	systable_endscan(tgscan);
@@ -1261,7 +1300,7 @@ renametrig(Oid relid,
 	/*
 	 * Close rel, but keep exclusive lock!
 	 */
-	heap_close(targetrel, NoLock);
+	relation_close(targetrel, NoLock);
 }
 
 

src/backend/commands/typecmds.c

@@ -3121,8 +3121,7 @@ RenameType(List *names, const char *newTypeName)
 	 * RenameRelationInternal will call RenameTypeInternal automatically.
 	 */
 	if (typTup->typtype == TYPTYPE_COMPOSITE)
-		RenameRelationInternal(typTup->typrelid, newTypeName,
-							   typTup->typnamespace);
+		RenameRelationInternal(typTup->typrelid, newTypeName);
 	else
 		RenameTypeInternal(typeOid, newTypeName,
 						   typTup->typnamespace);

src/include/commands/tablecmds.h

@@ -45,15 +45,12 @@ extern void ExecuteTruncate(TruncateStmt *stmt);
 
 extern void SetRelationHasSubclass(Oid relationId, bool relhassubclass);
 
-extern void renameatt(Oid myrelid, RenameStmt *stmt);
+extern void renameatt(RenameStmt *stmt);
 
-extern void RenameRelation(Oid myrelid,
-			   const char *newrelname,
-			   ObjectType reltype);
+extern void RenameRelation(RenameStmt *stmt);
 
 extern void RenameRelationInternal(Oid myrelid,
-					   const char *newrelname,
-					   Oid namespaceId);
+					   const char *newrelname);
 
 extern void find_composite_type_dependencies(Oid typeOid,
 								 Relation origRelation,

src/include/commands/trigger.h

@@ -115,7 +115,7 @@ extern Oid CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
 extern void RemoveTriggerById(Oid trigOid);
 extern Oid	get_trigger_oid(Oid relid, const char *name, bool missing_ok);
 
-extern void renametrig(Oid relid, const char *oldname, const char *newname);
+extern void renametrig(RenameStmt *stmt);
 
 extern void EnableDisableTrigger(Relation rel, const char *tgname,
 					 char fires_when, bool skip_system);