postreviews fix (SCRUM related)

reordered Item_row class variables to be sorted by memory size

mysql-test/r/subselect.result

@@ -39,9 +39,8 @@ Reference 'a' not supported (forward reference in item list)
 EXPLAIN SELECT 1 FROM (SELECT 1 as a) as b  HAVING (SELECT a)=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
+3	DEPENDENT SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
-Warnings:
-Note	1247	Select 3 was reduced during optimisation
 SELECT 1 FROM (SELECT 1 as a) as b HAVING (SELECT a)=1;
 1
 1

sql/item.cc

@@ -1289,9 +1289,10 @@ bool Item_cache_row::setup(Item * item)
     return 1;
   for (uint i= 0; i < item_count; i++)
   {
-    if (!(values[i]= Item_cache::get_cache(item->el(i)->result_type())))
+    Item *el= item->el(i);
+    if (!(values[i]= Item_cache::get_cache(el->result_type())))
       return 1;
-    values[i]->setup(item->el(i));
+    values[i]->setup(el);
   }
   return 0;
 }

sql/item.h

@@ -515,6 +515,10 @@ class Item_ref_null_helper: public Item_ref
 
 /*
   Used to find item in list of select items after '*' items processing.
+
+  Because item '*' can be used in item list. when we create
+  Item_ref_on_list_position we do not know how item list will be changed, but
+  we know number of item position (I mean queries like "select * from t").
 */
 class Item_ref_on_list_position: public Item_ref_null_helper
 {

sql/item_cmpfunc.h

@@ -97,6 +97,13 @@ class Item_in_optimizer: public Item_bool_func
   bool preallocate_row();
   bool fix_fields(THD *, struct st_table_list *, Item **);
   bool is_null();
+  /*
+    Item_in_optimizer item is special boolean function. On value request 
+    (one of val, val_int or val_str methods) it evaluate left expression 
+    of IN by storing it value in cache item (one of Item_cache* items), 
+    then it test cache is it NULL. If left expression (cache) is NULL then
+    Item_in_optimizer return NULL, else it evaluate Item_in_subselect.
+  */
   longlong val_int();
   
   Item_cache **get_cache() { return &cache; }
@@ -546,8 +553,10 @@ class cmp_item_row :public cmp_item
   {
     if (comparators)
       for (uint i= 0; i < n; i++)
+      {
 	if (comparators[i])
 	  delete comparators[i];
+      }
   }
   void store_value(Item *item);
   int cmp(Item *arg);

sql/item_row.cc

@@ -54,7 +54,14 @@ bool Item_row::fix_fields(THD *thd, TABLE_LIST *tabl, Item **ref)
     if (items[i]->fix_fields(thd, tabl, items+i))
       return 1;
     used_tables_cache |= items[i]->used_tables();
-    const_item_cache&= items[i]->const_item();
+    if (const_item_cache&= items[i]->const_item() && !with_null)
+      if (items[i]->cols() > 1)
+	with_null|= items[i]->null_inside();
+      else
+      {
+	items[i]->val_int();
+	with_null|= items[i]->null_value;
+      }
     maybe_null|= items[i]->maybe_null;
   }
   return 0;
@@ -82,25 +89,6 @@ bool Item_row::check_cols(uint c)
   return 0;
 }
 
-bool Item_row::null_inside()
-{
-  for (uint i= 0; i < arg_count; i++)
-  {
-    if (items[i]->cols() > 1)
-    {
-      if (items[i]->null_inside())
-	return 1;
-    }
-    else
-    {
-      items[i]->val_int();
-      if (items[i]->null_value)
-	return 1;
-    }
-  }
-  return 0;
-}
-
 void Item_row::bring_value()
 {
   for (uint i= 0; i < arg_count; i++)

sql/item_row.h

@@ -16,19 +16,22 @@
 
 class Item_row: public Item
 {
-  bool array_holder;
+  Item **items;
   table_map used_tables_cache;
-  bool const_item_cache;
   uint arg_count;
-  Item **items;
+  bool array_holder;
+  bool const_item_cache;
+  bool with_null;
 public:
   Item_row(List<Item> &);
   Item_row(Item_row *item):
-    Item(), array_holder(0), 
+    Item(),
+    items(item->items),
     used_tables_cache(item->used_tables_cache),
-    const_item_cache(item->const_item_cache),
     arg_count(item->arg_count),
-    items(item->items)
+    array_holder(0), 
+    const_item_cache(item->const_item_cache),
+    with_null(0)
   {}
 
   ~Item_row()
@@ -71,6 +74,6 @@ class Item_row: public Item
   Item* el(uint i) { return items[i]; }
   Item** addr(uint i) { return items + i; }
   bool check_cols(uint c);
-  bool null_inside();
+  bool null_inside() { return with_null; };
   void bring_value();
 };

sql/item_strfunc.cc

@@ -1961,7 +1961,8 @@ String *Item_func_conv_charset::val_str(String *str)
   d0=d=(unsigned char*)str->ptr();
   de=d+dmaxlen;
 
-  while (s < se && d < de){
+  while (s < se && d < de)
+  {
 
     cnvres=from->mb_wc(from,&wc,s,se);
     if (cnvres>0)

sql/item_subselect.cc

@@ -157,7 +157,11 @@ void Item_singlerow_subselect::select_transformer(THD *thd,
   SELECT_LEX *select_lex= unit->first_select();
   
   if (!select_lex->next_select() && !select_lex->table_list.elements &&
-      select_lex->item_list.elements == 1)
+      select_lex->item_list.elements == 1 &&
+      // TODO: mark subselect items from item list separately
+      !(select_lex->item_list.head()->type() == FIELD_ITEM ||
+	select_lex->item_list.head()->type() == REF_ITEM)
+      )
   {
     
     have_to_be_excluded= 1;
@@ -170,9 +174,6 @@ void Item_singlerow_subselect::select_transformer(THD *thd,
     }
     substitution= select_lex->item_list.head();
     substitution->set_outer_resolving();
-    if (substitution->type() == FIELD_ITEM ||
-	substitution->type() == REF_ITEM)
-      name= substitution->name; // Save name for correct resolving
      
     if (select_lex->where || select_lex->having)
     {
@@ -444,6 +445,9 @@ void Item_in_subselect::single_value_transformer(THD *thd,
 	     "LIMIT & IN/ALL/ANY/SOME subquery");
     DBUG_VOID_RETURN;
   }
+  // no sense in ORDER BY without LIMIT
+  unit->global_parameters->order_list.empty();
+
   Item_in_optimizer *optimizer;
   substitution= optimizer= new Item_in_optimizer(left_expr, this);
   if (!optimizer)
@@ -476,18 +480,16 @@ void Item_in_subselect::single_value_transformer(THD *thd,
     else
       item= (Item*) sl->item_list.pop();
 
-    if (sl->having || sl->with_sum_func || sl->group_list.first ||
-	sl->order_list.first)
+    sl->order_list.empty(); // no sense in ORDER BY without LIMIT
+
+    if (sl->having || sl->with_sum_func || sl->group_list.first)
     {
       sl->item_list.push_back(item);
       item= (*func)(expr, new Item_ref_null_helper(this,
 						   sl->item_list.head_ref(),
 						   (char *)"<no matter>",
 						   (char*)"<result>"));
-      if (sl->having || sl->with_sum_func || sl->group_list.first)
-	sl->having= and_items(sl->having, item);
-      else
-	sl->where= and_items(sl->where, item);
+      sl->having= and_items(sl->having, item);
     }
     else
     {
@@ -547,10 +549,22 @@ void Item_in_subselect::row_value_transformer(THD *thd,
   if (unit->global_parameters->select_limit != 
       HA_POS_ERROR)
   {
+    /*
+      Because we do the following (not exactly, following is just explenation) 
+      transformation
+      SELECT * from t1 WHERE t1.a IN (SELECT t2.a FROM t2)
+        ->
+      SELECT * from t1 WHERE EXISTS(SELECT 1 FROM t2 t1.a = t2.a LIMIT 1)
+
+      it's impossible to support limit in the sub select.
+    */
     my_error(ER_NOT_SUPPORTED_YET, MYF(0),
 	     "LIMIT & IN/ALL/ANY/SOME subquery");
     DBUG_VOID_RETURN;
   }
+  // no sense in ORDER BY without LIMIT
+  unit->global_parameters->order_list.empty();
+
   Item_in_optimizer *optimizer;
   substitution= optimizer= new Item_in_optimizer(left_expr, this);
   if (!optimizer)
@@ -568,6 +582,7 @@ void Item_in_subselect::row_value_transformer(THD *thd,
 	       "LIMIT & IN/ALL/ANY/SOME subquery");
       DBUG_VOID_RETURN;
     }
+    sl->order_list.empty(); // no sense in ORDER BY without LIMIT
 
     sl->dependent= 1;
 
@@ -589,7 +604,7 @@ void Item_in_subselect::row_value_transformer(THD *thd,
     }
 
     if (sl->having || sl->with_sum_func || sl->group_list.first ||
-	!sl->table_list.elements)
+	!sl->table_list.elements || !sl->table_list.elements)
       sl->having= and_items(sl->having, item);
     else
       sl->where= and_items(sl->where, item);