1 files changed, 17 insertions, 5 deletions
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 24854713a0e..5f0370a5a32 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -166,11 +166,23 @@ class JOIN :public Sql_alloc
   JOIN *tmp_join; // copy of this JOIN to be used with temporary tables
   ROLLUP rollup;				// Used with rollup
 
-  bool select_distinct, //Is select distinct?
-    no_order, simple_order, simple_group,
-    skip_sort_order, need_tmp,
-    hidden_group_fields,
-    buffer_result;
+  bool select_distinct;				// Set if SELECT DISTINCT
+
+  /*
+    simple_xxxxx is set if ORDER/GROUP BY doesn't include any references
+    to other tables than the first non-constant table in the JOIN.
+    It's also set if ORDER/GROUP BY is empty.
+  */
+  bool simple_order, simple_group;
+  /*
+    Is set only in case if we have a GROUP BY clause
+    and no ORDER BY after constant elimination of 'order'.
+  */
+  bool no_order;
+  /* Is set if we have a GROUP BY and we have ORDER BY on a constant. */
+  bool          skip_sort_order;
+
+  bool need_tmp, hidden_group_fields, buffer_result;
   DYNAMIC_ARRAY keyuse;
   Item::cond_result cond_value;
   List<Item> all_fields; // to store all fields that used in query