optimisation of independent ALL/ANY with aggregate function (WL#1115) (SCRUM)

mysql-test/r/subselect.result:
  test of new optimisation
mysql-test/t/subselect.test:
  test of new optimisation
sql/item_subselect.cc:
  special subselect to finding max/min of returned values
  optimisation of independent ALL/ANY with aggregate function
sql/item_subselect.h:
  special subselect to finding max/min of returned values
sql/sql_class.cc:
  class for collaction result for max/min subquery
sql/sql_class.h:
  class for collaction result for max/min subquery

1 files changed, 10 insertions, 0 deletions

diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index 9cfa304bb47..d3aa8f59e49 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -130,6 +130,7 @@ public:
     max_length= item->max_length;
     decimals= item->decimals;
   }
+  Item_singlerow_subselect() :Item_subselect(), value(0), row (0) {}
 
   subs_type substype() { return SINGLEROW_SUBS; }
 
@@ -153,6 +154,15 @@ public:
   friend class select_singlerow_subselect;
 };
 
+/* used in static ALL/ANY optimisation */
+class Item_maxmin_subselect: public Item_singlerow_subselect
+{
+public:
+  Item_maxmin_subselect(THD *thd, st_select_lex *select_lex, bool max);
+  Item_maxmin_subselect(Item_maxmin_subselect *item)
+    :Item_singlerow_subselect(item) {}
+};
+
 /* exists subselect */
 
 class Item_exists_subselect :public Item_subselect