mdev-9864: cleanup, re-factoring.

Added comments.

Author: igorbabaev

sql/item_subselect.h

@@ -128,6 +128,11 @@ class Item_subselect :public Item_result_field,
   /* TRUE <=> The underlying SELECT is correlated w.r.t some ancestor select */
   bool is_correlated;
 
+  /* 
+    TRUE <=> the subquery contains a recursive reference in the FROM list
+    of one of its selects. In this case some of subquery optimization
+    strategies cannot be applied for the subquery;
+  */
   bool with_recursive_reference; 
 
   enum subs_type {UNKNOWN_SUBS, SINGLEROW_SUBS,

sql/share/errmsg-utf8.txt

@@ -7157,7 +7157,7 @@ ER_RECURSIVE_WITHOUT_ANCHORS
 ER_UNACCEPTABLE_MUTUAL_RECURSION
         eng "Unacceptable mutual recursion with anchored table '%s'"
 ER_REF_TO_RECURSIVE_WITH_TABLE_IN_DERIVED
-        eng "Reference to recursive WITH table '%s' in materiazed derived"
+        eng "Reference to recursive WITH table '%s' in materialized derived"
 ER_NOT_STANDARDS_COMPLIANT_RECURSIVE
         eng "Restrictions imposed on recursive definitions are violated for table '%s'"
 #

sql/sql_class.h

@@ -4682,10 +4682,12 @@ class select_union_recursive :public select_union
 {
  public:
   TABLE *incr_table;
+  TABLE *first_rec_table_to_update;
   List<TABLE> rec_tables;
 
   select_union_recursive(THD *thd_arg):
-    select_union(thd_arg), incr_table(0) {};
+    select_union(thd_arg),
+    incr_table(0), first_rec_table_to_update(0) {};
 
   int send_data(List<Item> &items);
   bool create_result_table(THD *thd, List<Item> *column_types,