diff --git a/internal/querynode/flow_graph_query_node.go b/internal/querynode/flow_graph_query_node.go
index cf559e0aec..687c3e0800 100644
--- a/internal/querynode/flow_graph_query_node.go
+++ b/internal/querynode/flow_graph_query_node.go
@@ -189,6 +189,7 @@ func (q *queryNodeFlowGraph) newDmInputNode(ctx context.Context, factory msgstre
 	return node
 }
 
+// consumerFlowGraph would consume by channel and subName
 func (q *queryNodeFlowGraph) consumerFlowGraph(channel Channel, subName ConsumeSubName) error {
 	if q.dmlStream == nil {
 		return errors.New("null dml message stream in flow graph")