diff --git a/src/backend/cdb/cdbdatalocality.c b/src/backend/cdb/cdbdatalocality.c
index e5e54cd..6e95130 100644
--- a/src/backend/cdb/cdbdatalocality.c
+++ b/src/backend/cdb/cdbdatalocality.c
@@ -4643,6 +4643,10 @@
 			}
 
 			if (enforce_virtual_segment_number > 0) {
+			  /*
+			   * this is the last factor to determine the virtual segment number,
+			   * it has the highest priority in all conditions.
+			   */
 				maxTargetSegmentNumber = enforce_virtual_segment_number;
 				minTargetSegmentNumber = enforce_virtual_segment_number;
 			}