diff --git a/internal/querynode/collection_replica.go b/internal/querynode/collection_replica.go
index 4bcf32837b..69d7e61ead 100644
--- a/internal/querynode/collection_replica.go
+++ b/internal/querynode/collection_replica.go
@@ -112,6 +112,7 @@ type ReplicaInterface interface {
 	queryRLock()
 	queryRUnlock()
 
+	// getSegmentsMemSize get the memory size in bytes of all the Segments
 	getSegmentsMemSize() int64
 	freeAll()
 	printReplica()