diff --git a/internal/querynode/collection_replica.go b/internal/querynode/collection_replica.go
index 59ef8db858..dda53e4625 100644
--- a/internal/querynode/collection_replica.go
+++ b/internal/querynode/collection_replica.go
@@ -455,6 +455,7 @@ func (colReplica *collectionReplica) removeSegmentPrivate(segmentID UniqueID) er
 	return nil
 }
 
+// getSegmentByID returns the segment which id is segmentID
 func (colReplica *collectionReplica) getSegmentByID(segmentID UniqueID) (*Segment, error) {
 	colReplica.mu.RLock()
 	defer colReplica.mu.RUnlock()