4 files changed, 22 insertions, 14 deletions

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 68be4709771..5ecd2565b4d 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1661,14 +1661,14 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 			snprintf(NewToastName, NAMEDATALEN, "pg_toast_%u",
 					 OIDOldHeap);
 			RenameRelationInternal(newrel->rd_rel->reltoastrelid,
-								   NewToastName, true);
+								   NewToastName, true, false);
 
 			/* ... and its valid index too. */
 			snprintf(NewToastName, NAMEDATALEN, "pg_toast_%u_index",
 					 OIDOldHeap);
 
 			RenameRelationInternal(toastidx,
-								   NewToastName, true);
+								   NewToastName, true, true);
 		}
 		relation_close(newrel, NoLock);
 	}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 946119fa860..73da6c39c22 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -3044,7 +3044,7 @@ rename_constraint_internal(Oid myrelid,
 			|| con->contype == CONSTRAINT_UNIQUE
 			|| con->contype == CONSTRAINT_EXCLUSION))
 		/* rename the index; this renames the constraint as well */
-		RenameRelationInternal(con->conindid, newconname, false);
+		RenameRelationInternal(con->conindid, newconname, false, true);
 	else
 		RenameConstraintById(constraintOid, newconname);
 
@@ -3112,6 +3112,7 @@ RenameConstraint(RenameStmt *stmt)
 ObjectAddress
 RenameRelation(RenameStmt *stmt)
 {
+	bool		is_index = stmt->renameType == OBJECT_INDEX;
 	Oid			relid;
 	ObjectAddress address;
 
@@ -3123,7 +3124,8 @@ RenameRelation(RenameStmt *stmt)
 	 * Lock level used here should match RenameRelationInternal, to avoid lock
 	 * escalation.
 	 */
-	relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
+	relid = RangeVarGetRelidExtended(stmt->relation,
+									 is_index ? ShareUpdateExclusiveLock : AccessExclusiveLock,
 									 stmt->missing_ok ? RVR_MISSING_OK : 0,
 									 RangeVarCallbackForAlterRelation,
 									 (void *) stmt);
@@ -3137,7 +3139,7 @@ RenameRelation(RenameStmt *stmt)
 	}
 
 	/* Do the work */
-	RenameRelationInternal(relid, stmt->newname, false);
+	RenameRelationInternal(relid, stmt->newname, false, is_index);
 
 	ObjectAddressSet(address, RelationRelationId, relid);
 
@@ -3148,7 +3150,7 @@ RenameRelation(RenameStmt *stmt)
  *		RenameRelationInternal - change the name of a relation
  */
 void
-RenameRelationInternal(Oid myrelid, const char *newrelname, bool is_internal)
+RenameRelationInternal(Oid myrelid, const char *newrelname, bool is_internal, bool is_index)
 {
 	Relation	targetrelation;
 	Relation	relrelation;	/* for RELATION relation */
@@ -3157,11 +3159,16 @@ RenameRelationInternal(Oid myrelid, const char *newrelname, bool is_internal)
 	Oid			namespaceId;
 
 	/*
-	 * Grab an exclusive lock on the target table, index, sequence, view,
-	 * materialized view, or foreign table, which we will NOT release until
-	 * end of transaction.
+	 * Grab a lock on the target relation, which we will NOT release until end
+	 * of transaction.  We need at least a self-exclusive lock so that
+	 * concurrent DDL doesn't overwrite the rename if they start updating
+	 * while still seeing the old version.  The lock also guards against
+	 * triggering relcache reloads in concurrent sessions, which might not
+	 * handle this information changing under them.  For indexes, we can use a
+	 * reduced lock level because RelationReloadIndexInfo() handles indexes
+	 * specially.
 	 */
-	targetrelation = relation_open(myrelid, AccessExclusiveLock);
+	targetrelation = relation_open(myrelid, is_index ? ShareUpdateExclusiveLock : AccessExclusiveLock);
 	namespaceId = RelationGetNamespace(targetrelation);
 
 	/*
@@ -3214,7 +3221,7 @@ RenameRelationInternal(Oid myrelid, const char *newrelname, bool is_internal)
 	}
 
 	/*
-	 * Close rel, but keep exclusive lock!
+	 * Close rel, but keep lock!
 	 */
 	relation_close(targetrelation, NoLock);
 }
@@ -7076,7 +7083,7 @@ ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
 		ereport(NOTICE,
 				(errmsg("ALTER TABLE / ADD CONSTRAINT USING INDEX will rename index \"%s\" to \"%s\"",
 						indexName, constraintName)));
-		RenameRelationInternal(index_oid, constraintName, false);
+		RenameRelationInternal(index_oid, constraintName, false, true);
 	}
 
 	/* Extra checks needed if making primary key */
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index 66f7c577267..285a0be6436 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -3255,7 +3255,7 @@ RenameType(RenameStmt *stmt)
 	 * RenameRelationInternal will call RenameTypeInternal automatically.
 	 */
 	if (typTup->typtype == TYPTYPE_COMPOSITE)
-		RenameRelationInternal(typTup->typrelid, newTypeName, false);
+		RenameRelationInternal(typTup->typrelid, newTypeName, false, false);
 	else
 		RenameTypeInternal(typeOid, newTypeName,
 						   typTup->typnamespace);
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index 138de84e832..2afcd5be442 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -67,7 +67,8 @@ extern ObjectAddress RenameConstraint(RenameStmt *stmt);
 extern ObjectAddress RenameRelation(RenameStmt *stmt);
 
 extern void RenameRelationInternal(Oid myrelid,
-					   const char *newrelname, bool is_internal);
+					   const char *newrelname, bool is_internal,
+					   bool is_index);
 
 extern void find_composite_type_dependencies(Oid typeOid,
 								 Relation origRelation,