diff --git a/internal/datanode/segment_replica.go b/internal/datanode/segment_replica.go
index 5db9f78d5c..2d966b104e 100644
--- a/internal/datanode/segment_replica.go
+++ b/internal/datanode/segment_replica.go
@@ -35,6 +35,7 @@ const (
 	maxBloomFalsePositive float64 = 0.005
 )
 
+// Replica is DataNode unique replication
 type Replica interface {
 	getCollectionID() UniqueID
 	getCollectionSchema(collectionID UniqueID, ts Timestamp) (*schemapb.CollectionSchema, error)