diff --git a/internal/querynode/flow_graph_filter_delete_node.go b/internal/querynode/flow_graph_filter_delete_node.go
index 0643cb38fd..aa66980660 100644
--- a/internal/querynode/flow_graph_filter_delete_node.go
+++ b/internal/querynode/flow_graph_filter_delete_node.go
@@ -26,6 +26,7 @@ import (
 	"go.uber.org/zap"
 )
 
+// filterDeleteNode is one of the nodes in delta flow graph
 type filterDeleteNode struct {
 	baseNode
 	collectionID UniqueID