keep old engine & JOIN if we changed subquery Item (Bug #3646)

mysql-test/r/subselect.result:
  ALL/ANY test
mysql-test/t/subselect.test:
  ALL/ANY test
sql/item_subselect.cc:
  keep old engine & JOIN if we changed subquery Item, which allow avoid second all SELECT items fix_fields call with pervios clean up (because of second setup_tables which remove table->key_use and maybe something else)
  keep list when we change Item in SELECT list
  processing inserted max/min function (now JOIN::prepare will be called only once)
  methods of changing item for subselect engines
sql/item_subselect.h:
  change item & results procedure
sql/item_sum.cc:
  Item_sum_hybrid::clear moved to .cc file (to keep .h clean and to make inserving/removing debug info easy)
sql/item_sum.h:
  Item_sum_hybrid::clear moved to .cc file (to keep .h clean and to make inserving/removing debug info easy)
sql/sql_lex.cc:
  note about new method
sql/sql_lex.h:
  method for changing result of UNION JOINs
sql/sql_select.cc:
  method for changing result in JOIN
sql/sql_select.h:
  method for changing result in JOIN
sql/sql_union.cc:
  method for changing result in JOIN

1 files changed, 98 insertions, 9 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 2d10be62d53..4503c1b63a9 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -56,10 +56,24 @@ void Item_subselect::init(st_select_lex *select_lex,
   DBUG_PRINT("subs", ("select_lex 0x%xl", (ulong) select_lex));
   unit= select_lex->master_unit();
 
-  if (select_lex->next_select())
-    engine= new subselect_union_engine(unit, result, this);
+  if (unit->item)
+  {
+    /*
+      Item can be changed in JOIN::prepare while engine in JOIN::optimize
+      => we do not copy old_engine here
+    */
+    engine= unit->item->engine;
+    unit->item->engine= 0;
+    unit->item= this;
+    engine->change_item(this, result);
+  }
   else
-    engine= new subselect_single_select_engine(select_lex, result, this);
+  {
+    if (select_lex->next_select())
+      engine= new subselect_union_engine(unit, result, this);
+    else
+      engine= new subselect_single_select_engine(select_lex, result, this);
+  }
   DBUG_VOID_RETURN;
 }
 
@@ -69,11 +83,13 @@ void Item_subselect::cleanup()
   Item_result_field::cleanup();
   if (old_engine)
   {
-    engine->cleanup();
+    if (engine)
+      engine->cleanup();
     engine= old_engine;
     old_engine= 0;
   }
-  engine->cleanup();
+  if (engine)
+    engine->cleanup();
   reset();
   value_assigned= 0;
   DBUG_VOID_RETURN;
@@ -127,7 +143,6 @@ bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
       if (have_to_be_excluded)
 	engine->exclude();
       substitution= 0;
-      fixed= 1;
       thd->where= "checking transformed subquery";      
       if (!(*ref)->fixed)
 	ret= (*ref)->fix_fields(thd, tables, ref);
@@ -660,10 +675,20 @@ Item_in_subselect::single_value_transformer(JOIN *join,
 	item= new Item_sum_min(*select_lex->ref_pointer_array);
       }
       *select_lex->ref_pointer_array= item;
-      select_lex->item_list.empty();
-      select_lex->item_list.push_back(item);
+      {
+	List_iterator<Item> it(select_lex->item_list);
+	it++;
+	it.replace(item);
+      }
 
-      // fix_fields call for 'item' will be made during new subquery fix_fields
+      /*
+	Item_sum_(max|min) can't substitute other item => we can use 0 as
+	reference
+      */
+      if (item->fix_fields(thd, join->tables_list, 0))
+	goto err;
+      /* we added aggregate function => we have to change statistic */
+      count_field_types(&join->tmp_table_param, join->all_fields, 0);
 
       subs= new Item_singlerow_subselect(select_lex);
     }
@@ -1428,3 +1453,67 @@ void subselect_indexsubquery_engine::print(String *str)
   }
   str->append(')');
 }
+
+/*
+  change select_result object of engine
+
+  SINOPSYS
+    subselect_single_select_engine::change_result()
+    si		new subselect Item
+    res		new select_result object
+
+  RETURN
+    0  OK
+    -1 error
+*/
+
+int subselect_single_select_engine::change_item(Item_subselect *si,
+						select_subselect *res)
+{
+  item= si;
+  result= res;
+  return select_lex->join->change_result(result);
+}
+
+
+/*
+  change select_result object of engine
+
+  SINOPSYS
+    subselect_single_select_engine::change_result()
+    si		new subselect Item
+    res		new select_result object
+
+  RETURN
+    0  OK
+    -1 error
+*/
+
+int subselect_union_engine::change_item(Item_subselect *si,
+					select_subselect *res)
+{
+  item= si;
+  int rc= unit->change_result(res, result);
+  result= res;
+  return rc;
+}
+
+
+/*
+  change select_result emulation, never should be called
+
+  SINOPSYS
+    subselect_single_select_engine::change_result()
+    si		new subselect Item
+    res		new select_result object
+
+  RETURN
+    -1 error
+*/
+
+int subselect_uniquesubquery_engine::change_item(Item_subselect *si,
+						 select_subselect *res)
+{
+  DBUG_ASSERT(0);
+  return -1;
+}