diff --git a/internal/querynode/collection.go b/internal/querynode/collection.go
index 870a8a38f5..7a0ffe73ed 100644
--- a/internal/querynode/collection.go
+++ b/internal/querynode/collection.go
@@ -61,6 +61,7 @@ func (c *Collection) Schema() *schemapb.CollectionSchema {
 	return c.schema
 }
 
+// addPartitionID would add a partition id to partition id list of collection
 func (c *Collection) addPartitionID(partitionID UniqueID) {
 	c.releaseMu.Lock()
 	defer c.releaseMu.Unlock()