diff --git a/pkg/common/storage/database/mgo/version_log.go b/pkg/common/storage/database/mgo/version_log.go
index 3929d7031..85b17f9be 100644
--- a/pkg/common/storage/database/mgo/version_log.go
+++ b/pkg/common/storage/database/mgo/version_log.go
@@ -34,7 +34,9 @@ func (l *VersionLogMgo) initIndex(ctx context.Context) error {
 		Keys: bson.M{
 			"d_id": 1,
 		},
+		Options: options.Index().SetUnique(true),
 	})
+
 	return err
 }