diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 1e3af0093b4..7bfc87d737d 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -2402,7 +2402,9 @@ makeObjectName(const char *name1, const char *name2, const char *label)
  * constraint names.)
  *
  * Note: it is theoretically possible to get a collision anyway, if someone
- * else chooses the same name concurrently.  This is fairly unlikely to be
+ * else chooses the same name concurrently.  We shorten the race condition
+ * window by checking for conflicting relations using SnapshotDirty, but
+ * that doesn't close the window entirely.  This is fairly unlikely to be
  * a problem in practice, especially if one is holding an exclusive lock on
  * the relation identified by name1.  However, if choosing multiple names
  * within a single command, you'd better create the new object and do
@@ -2418,15 +2420,45 @@ ChooseRelationName(const char *name1, const char *name2,
 	int			pass = 0;
 	char	   *relname = NULL;
 	char		modlabel[NAMEDATALEN];
+	SnapshotData SnapshotDirty;
+	Relation	pgclassrel;
+
+	/* prepare to search pg_class with a dirty snapshot */
+	InitDirtySnapshot(SnapshotDirty);
+	pgclassrel = table_open(RelationRelationId, AccessShareLock);
 
 	/* try the unmodified label first */
 	strlcpy(modlabel, label, sizeof(modlabel));
 
 	for (;;)
 	{
+		ScanKeyData key[2];
+		SysScanDesc scan;
+		bool		collides;
+
 		relname = makeObjectName(name1, name2, modlabel);
 
-		if (!OidIsValid(get_relname_relid(relname, namespaceid)))
+		/* is there any conflicting relation name? */
+		ScanKeyInit(&key[0],
+					Anum_pg_class_relname,
+					BTEqualStrategyNumber, F_NAMEEQ,
+					CStringGetDatum(relname));
+		ScanKeyInit(&key[1],
+					Anum_pg_class_relnamespace,
+					BTEqualStrategyNumber, F_OIDEQ,
+					ObjectIdGetDatum(namespaceid));
+
+		scan = systable_beginscan(pgclassrel, ClassNameNspIndexId,
+								  true /* indexOK */ ,
+								  &SnapshotDirty,
+								  2, key);
+
+		collides = HeapTupleIsValid(systable_getnext(scan));
+
+		systable_endscan(scan);
+
+		/* break out of loop if no conflict */
+		if (!collides)
 		{
 			if (!isconstraint ||
 				!ConstraintNameExists(relname, namespaceid))
@@ -2438,6 +2470,8 @@ ChooseRelationName(const char *name1, const char *name2,
 		snprintf(modlabel, sizeof(modlabel), "%s%d", label, ++pass);
 	}
 
+	table_close(pgclassrel, AccessShareLock);
+
 	return relname;
 }