diff --git a/internal/querynode/collection_replica.go b/internal/querynode/collection_replica.go
index 69d7e61ead..1677c485a5 100644
--- a/internal/querynode/collection_replica.go
+++ b/internal/querynode/collection_replica.go
@@ -109,6 +109,7 @@ type ReplicaInterface interface {
 	// query mu
 	queryLock()
 	queryUnlock()
+	// queryRLock guards query and delete segment operations
 	queryRLock()
 	queryRUnlock()