diff --git a/internal/datanode/flow_graph_insert_buffer_node.go b/internal/datanode/flow_graph_insert_buffer_node.go
index d8ef9887af..03ebb897b0 100644
--- a/internal/datanode/flow_graph_insert_buffer_node.go
+++ b/internal/datanode/flow_graph_insert_buffer_node.go
@@ -82,6 +82,7 @@ type segmentFlushUnit struct {
 	flushed        bool
 }
 
+// BufferData buffers insert data, monitoring buffer size and limit
 type BufferData struct {
 	buffer *InsertData
 	size   int64