subselect transformation moved in after-fix_field place

removed "of is null" if it is possible
  (this cset should be SCRUM related, but not approved as scrum task yet)

mysql-test/r/subselect.result

@@ -46,7 +46,7 @@ SELECT 1 FROM (SELECT 1 as a) as b HAVING (SELECT a)=1;
 1
 1
 SELECT (SELECT 1), a;
-Unknown column 'a' in 'field list'
+Unknown column 'a' in 'checking transformed subquery'
 SELECT 1 as a FROM (SELECT 1) as b HAVING (SELECT a)=1;
 a
 1
@@ -668,7 +668,6 @@ id
 EXPLAIN SELECT * FROM t2 WHERE id IN (SELECT 1+(select 1));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	ref	id	id	5	const	1	Using where; Using index
-3	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 Warnings:
 Note	1247	Select 3 was reduced during optimisation
 Note	1247	Select 2 was reduced during optimisation
@@ -1008,7 +1007,7 @@ CREATE TABLE t1 SELECT (SELECT 1 as a UNION SELECT 1+1 limit 1,1) as a;
 SHOW CREATE TABLE t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `a` bigint(1) NOT NULL default '0'
+  `a` bigint(17) NOT NULL default '0'
 ) TYPE=MyISAM CHARSET=latin1
 drop table t1;
 create table t1 (a int);

sql/item.cc

@@ -1324,17 +1324,15 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
     }
   }
 
-/*
- * The following conditional is changed as to correctly identify 
- * incorrect references in group functions or forward references 
- * with sub-select's / derived tables, while it prevents this 
- * check when Item_ref is created in an expression involving 
- * summing function, which is to be placed in the user variable.
- *
- */
- 
+  /*
+    The following conditional is changed as to correctly identify 
+    incorrect references in group functions or forward references 
+    with sub-select's / derived tables, while it prevents this 
+    check when Item_ref is created in an expression involving 
+    summing function, which is to be placed in the user variable.
+  */
   if (((*ref)->with_sum_func && name &&
-       (depended_from || 
+       (depended_from ||
 	!(thd->lex.current_select->linkage != GLOBAL_OPTIONS_TYPE &&
 	  thd->lex.current_select->select_lex()->having_fix_field))) ||
       !(*ref)->fixed)

sql/item.h

@@ -100,7 +100,7 @@ class Item {
   virtual bool get_time(TIME *ltime);
   virtual bool get_date_result(TIME *ltime,bool fuzzydate)
   { return get_date(ltime,fuzzydate); }
-  virtual bool is_null() { return 0; };
+  virtual bool is_null() { return 0; }
   virtual void top_level_item() {}
   virtual void set_result_field(Field *field) {}
   virtual bool is_result_field() { return 0; }
@@ -560,6 +560,15 @@ class Item_ref_null_helper: public Item_ref
   longlong val_int();
   String* val_str(String* s);
   bool get_date(TIME *ltime, bool fuzzydate);
+  void print(String *str)
+  {
+    str->append("ref_null_helper(");
+    if (ref && *ref)
+      (*ref)->print(str);
+    else
+      str->append('?');
+    str->append(')');
+  }
 };
 
 
@@ -605,6 +614,15 @@ class Item_asterisk_remover :public Item_ref_null_helper
   {}
   bool fix_fields(THD *, struct st_table_list *, Item ** ref);
   Item **storage() {return &item;}
+  void print(String *str)
+  {
+    str->append("ref_null_helper('");
+    if (item)
+      item->print(str);
+    else
+      str->append('?');
+    str->append(')');
+  }
 };
 
 /*

sql/item_cmpfunc.cc

@@ -318,16 +318,24 @@ int Arg_comparator::compare_e_row()
   return 1;
 }
 
-bool Item_in_optimizer::preallocate_row()
+
+bool Item_in_optimizer::fix_left(THD *thd,
+				 struct st_table_list *tables,
+				 Item **ref)
 {
-  return (!(cache= Item_cache::get_cache(ROW_RESULT)));
+  if (args[0]->fix_fields(thd, tables, ref) ||
+      (!cache && !(cache= Item_cache::get_cache(args[0]->result_type()))))
+    return 1;
+  cache->setup(args[0]);
+  return 0;
 }
 
 
+
 bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
 				   Item ** ref)
 {
-  if (args[0]->fix_fields(thd, tables, args))
+  if (fix_left(thd, tables, ref))
     return 1;
   if (args[0]->maybe_null)
     maybe_null=1;
@@ -340,9 +348,6 @@ bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
   with_sum_func= args[0]->with_sum_func;
   used_tables_cache= args[0]->used_tables();
   const_item_cache= args[0]->const_item();
-  if (!cache && !(cache= Item_cache::get_cache(args[0]->result_type())))
-    return 1;
-  cache->setup(args[0]);
   if (cache->cols() == 1)
   {
     if (args[0]->used_tables())
@@ -361,7 +366,7 @@ bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
 	((Item_cache *)cache->el(i))->set_used_tables(0);
     }
   }
-  if (args[1]->fix_fields(thd, tables, args))
+  if (!args[1]->fixed && args[1]->fix_fields(thd, tables, args))
     return 1;
   Item_in_subselect * sub= (Item_in_subselect *)args[1];
   if (args[0]->cols() != sub->engine->cols())
@@ -1592,7 +1597,8 @@ Item_cond::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     }
     if (abort_on_null)
       item->top_level_item();
-    if (item->fix_fields(thd, tables, li.ref()) || item->check_cols(1))
+    if ((!item->fixed &&
+	 item->fix_fields(thd, tables, li.ref())) || item->check_cols(1))
       return 1; /* purecov: inspected */
     used_tables_cache|=item->used_tables();
     with_sum_func= with_sum_func || item->with_sum_func;

sql/item_cmpfunc.h

@@ -91,9 +91,8 @@ class Item_in_optimizer: public Item_bool_func
 public:
   Item_in_optimizer(Item *a, Item_in_subselect *b):
     Item_bool_func(a, (Item *)b), cache(0) {}
-  // used by row in transformer
-  bool preallocate_row();
   bool fix_fields(THD *, struct st_table_list *, Item **);
+  bool fix_left(THD *thd, struct st_table_list *tables, Item **ref);
   bool is_null();
   /*
     Item_in_optimizer item is special boolean function. On value request 
@@ -103,7 +102,7 @@ class Item_in_optimizer: public Item_bool_func
     Item_in_optimizer return NULL, else it evaluate Item_in_subselect.
   */
   longlong val_int();
-  
+  const char *func_name() const { return "IN_OPTIMIZER"; }
   Item_cache **get_cache() { return &cache; }
 };
 

sql/item_subselect.h

@@ -46,6 +46,8 @@ class Item_subselect :public Item_result_field
   bool have_to_be_excluded;
 
 public:
+  enum trans_res {OK, REDUCE, ERROR};
+
   Item_subselect();
   Item_subselect(Item_subselect *item)
   {
@@ -71,7 +73,7 @@ class Item_subselect :public Item_result_field
   {
     null_value= 1;
   }
-  virtual void select_transformer(THD *thd, st_select_lex_unit *unit);
+  virtual trans_res select_transformer(THD *thd, JOIN *join);
   bool assigned() { return value_assigned; }
   void assigned(bool a) { value_assigned= a; }
   enum Type type() const;
@@ -83,6 +85,13 @@ class Item_subselect :public Item_result_field
   bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref);
   virtual void fix_length_and_dec();
   table_map used_tables() const;
+  void print(String *str)
+  {
+    if (name)
+      str->append(name);
+    else
+      str->append("-subselect-");
+  }
 
   friend class select_subselect;
   friend class Item_in_optimizer;
@@ -105,7 +114,7 @@ class Item_singlerow_subselect :public Item_subselect
     decimals= item->decimals;
   }
   void reset();
-  void select_transformer(THD *thd, st_select_lex_unit *unit);
+  trans_res select_transformer(THD *thd, JOIN *join);
   void store(uint i, Item* item);
   double val();
   longlong val_int ();
@@ -161,25 +170,35 @@ class Item_in_subselect :public Item_exists_subselect
 {
 protected:
   Item * left_expr;
+  /*
+    expr & optinizer used in subselect rewriting to store Item for
+    all JOIN in UNION
+  */
+  Item *expr;
+  Item_in_optimizer *optimizer;
   bool was_null;
+  bool abort_on_null;
 public:
   Item_in_subselect(THD *thd, Item * left_expr, st_select_lex *select_lex);
   Item_in_subselect(Item_in_subselect *item);
-  Item_in_subselect(): Item_exists_subselect() {}
+  Item_in_subselect(): Item_exists_subselect(),  abort_on_null(0)  {}
   void reset() 
   {
     value= 0;
     null_value= 0;
     was_null= 0;
   }
-  virtual void select_transformer(THD *thd, st_select_lex_unit *unit);
-  void single_value_transformer(THD *thd, st_select_lex_unit *unit,
-				Item *left_expr, compare_func_creator func);
-  void row_value_transformer(THD *thd, st_select_lex_unit *unit,
-			     Item *left_expr);
+  trans_res select_transformer(THD *thd, JOIN *join);
+  trans_res single_value_transformer(THD *thd, JOIN *join,
+				     Item *left_expr,
+				     compare_func_creator func);
+  trans_res row_value_transformer(THD *thd, JOIN * join,
+				  Item *left_expr);
   longlong val_int();
   double val();
   String *val_str(String*);
+  void top_level_item() { abort_on_null=1; }
+  bool test_limit(st_select_lex_unit *unit);
 
   friend class Item_asterisk_remover;
   friend class Item_ref_null_helper;
@@ -196,7 +215,7 @@ class Item_allany_subselect :public Item_in_subselect
   Item_allany_subselect(THD *thd, Item * left_expr, compare_func_creator f,
 		     st_select_lex *select_lex);
   Item_allany_subselect(Item_allany_subselect *item);
-  virtual void select_transformer(THD *thd, st_select_lex_unit *unit);
+  trans_res select_transformer(THD *thd, JOIN *join);
 };
 
 class subselect_engine: public Sql_alloc

sql/sql_derived.cc

@@ -196,7 +196,8 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit,
 	    if (tables)
 	    {
 	      for (TABLE_LIST *cursor= tables;  cursor;  cursor= cursor->next)
-		cursor->table_list->table=cursor->table;
+		if (cursor->table_list)
+		  cursor->table_list->table=cursor->table;
 	    }
 	  }
 	  else

sql/sql_lex.cc

@@ -1302,11 +1302,13 @@ bool st_select_lex_unit::create_total_list_n_last_return(THD *thd, st_lex *lex,
 	    return 1;
 	  }
 	  *new_table_list= cursor;
+	  cursor->table_list= aux; //to be able mark this table as shared
 	  new_table_list= &cursor->next;
 	  *new_table_list= 0;			// end result list
 	}
 	else
-	  aux->shared= 1;			// Mark that it's used twice
+	  // Mark that it's used twice
+	  cursor->table_list->shared= aux->shared= 1;
 	aux->table_list= cursor;
       }
     }
@@ -1403,6 +1405,7 @@ ulong st_select_lex::get_table_join_options()
 }
 
 st_select_lex::st_select_lex(struct st_lex *lex)
+  :fake_select(0)
 {
   select_number= ++lex->thd->select_number;
   init_query();

sql/sql_lex.h

@@ -352,6 +352,8 @@ class st_select_lex: public st_select_lex_node
   bool  braces;   	/* SELECT ... UNION (SELECT ... ) <- this braces */
   /* TRUE when having fix field called in processing of this SELECT */
   bool having_fix_field;
+  /* TRUE for fake select, which used in UNION processing */
+  bool fake_select;
 
   void init_query();
   void init_select();
@@ -405,7 +407,7 @@ class st_select_lex: public st_select_lex_node
   
   friend void mysql_init_query(THD *thd);
   st_select_lex(struct st_lex *lex);
-  st_select_lex() {}
+  st_select_lex() :fake_select(0) {}
   void make_empty_select(st_select_lex *last_select)
   {
     select_number=INT_MAX;

sql/sql_olap.cc

@@ -150,7 +150,8 @@ int handle_olaps(LEX *lex, SELECT_LEX *select_lex)
   {
     if (cursor->do_redirect)
     {
-      cursor->table= ((TABLE_LIST*) cursor->table)->table;
+      //Sinisa TODO: there are function for this purpose: fix_tables_pointers
+      cursor->table= cursor->table_list->table;
       cursor->do_redirect= 0;
     }
   }

sql/sql_select.cc

@@ -201,7 +201,8 @@ void relink_tables(SELECT_LEX *select_lex)
   for (TABLE_LIST *cursor= (TABLE_LIST *) select_lex->table_list.first;
        cursor;
        cursor=cursor->next)
-    cursor->table= cursor->table_list->table;
+    if (cursor->table_list)
+      cursor->table= cursor->table_list->table;
 }
 
 
@@ -314,6 +315,19 @@ JOIN::prepare(Item ***rref_pointer_array,
       having->split_sum_func(ref_pointer_array, all_fields);
   }
   
+  // Is it subselect
+  {
+    Item_subselect *subselect;
+    if ((subselect= select_lex->master_unit()->item) &&
+	!select_lex->fake_select)
+    {
+      Item_subselect::trans_res res;
+      if ((res= subselect->select_transformer(thd, this)) !=
+	  Item_subselect::OK)
+	DBUG_RETURN((res == Item_subselect::ERROR));
+    }
+  }
+
   if (setup_ftfuncs(select_lex)) /* should be after having->fix_fields */
     DBUG_RETURN(-1);
   /*

sql/sql_union.cc

@@ -188,42 +188,33 @@ int st_select_lex_unit::prepare(THD *thd, select_result *sel_result,
   union_result->not_describe=1;
   union_result->tmp_table_param=tmp_table_param;
 
-  /*
-    The following piece of code is placed here solely for the purpose of 
-    getting correct results with EXPLAIN when UNION is withing a sub-select
-    or derived table ...
-  */
-
-  if (thd->lex.describe)
+  for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
   {
-    for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
-    {
-      JOIN *join= new JOIN(thd, sl->item_list, 
-			   sl->options | thd->options | SELECT_NO_UNLOCK,
-			   union_result);
-      thd->lex.current_select= sl;
-      offset_limit_cnt= sl->offset_limit;
-      select_limit_cnt= sl->select_limit+sl->offset_limit;
-      if (select_limit_cnt < sl->select_limit)
-	select_limit_cnt= HA_POS_ERROR;		// no limit
-      if (select_limit_cnt == HA_POS_ERROR)
-	sl->options&= ~OPTION_FOUND_ROWS;
-      
-      res= join->prepare(&sl->ref_pointer_array,
-			 (TABLE_LIST*) sl->table_list.first, sl->with_wild,
-			 sl->where,
-			 ((sl->braces) ? sl->order_list.elements : 0) +
-			 sl->group_list.elements,
-			 (sl->braces) ? 
-			 (ORDER *)sl->order_list.first : (ORDER *) 0,
-			 (ORDER*) sl->group_list.first,
-			 sl->having,
-			 (ORDER*) NULL,
-			 sl, this, t_and_f);
-      t_and_f= 0;
-      if (res || thd->is_fatal_error)
-	goto err;
-    }
+    JOIN *join= new JOIN(thd, sl->item_list, 
+			 sl->options | thd->options | SELECT_NO_UNLOCK,
+			 union_result);
+    thd->lex.current_select= sl;
+    offset_limit_cnt= sl->offset_limit;
+    select_limit_cnt= sl->select_limit+sl->offset_limit;
+    if (select_limit_cnt < sl->select_limit)
+      select_limit_cnt= HA_POS_ERROR;		// no limit
+    if (select_limit_cnt == HA_POS_ERROR)
+      sl->options&= ~OPTION_FOUND_ROWS;
+    
+    res= join->prepare(&sl->ref_pointer_array,
+		       (TABLE_LIST*) sl->table_list.first, sl->with_wild,
+		       sl->where,
+		       ((sl->braces) ? sl->order_list.elements : 0) +
+		       sl->group_list.elements,
+		       (sl->braces) ? 
+		       (ORDER *)sl->order_list.first : (ORDER *) 0,
+		       (ORDER*) sl->group_list.first,
+		       sl->having,
+		       (ORDER*) NULL,
+		       sl, this, t_and_f);
+    t_and_f= 0;
+    if (res || thd->is_fatal_error)
+      goto err;
   }
 
   item_list.empty();
@@ -268,14 +259,12 @@ int st_select_lex_unit::exec()
     }
     for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
     {
+      thd->lex.current_select= sl;
+
       if (optimized)
 	res= sl->join->reinit();
       else
       {
-	JOIN *join= new JOIN(thd, sl->item_list, 
-			     sl->options | thd->options | SELECT_NO_UNLOCK,
-			     union_result);
-	thd->lex.current_select= sl;
 	offset_limit_cnt= sl->offset_limit;
 	select_limit_cnt= sl->select_limit+sl->offset_limit;
 	if (select_limit_cnt < sl->select_limit)
@@ -283,22 +272,36 @@ int st_select_lex_unit::exec()
 	if (select_limit_cnt == HA_POS_ERROR)
 	  sl->options&= ~OPTION_FOUND_ROWS;
 	
-	res= join->prepare(&sl->ref_pointer_array,
-			   (TABLE_LIST*) sl->table_list.first, sl->with_wild,
-			   sl->where,
-			   ((sl->braces) ? sl->order_list.elements : 0) +
-			   sl->group_list.elements,
-			   (sl->braces) ? 
-			   (ORDER *)sl->order_list.first : (ORDER *) 0,
-			   (ORDER*) sl->group_list.first,
-			   sl->having,
-			   (ORDER*) NULL,
-			   sl, this, t_and_f);
-	t_and_f=0;
-	if (res | thd->is_fatal_error)
+	/* 
+	   As far as union share table space we should reassign table map,
+	   which can be spoiled by 'prepare' of JOIN of other UNION parts
+	   if it use same tables
+	*/
+	uint tablenr=0;
+	for (TABLE_LIST *table_list= (TABLE_LIST*) sl->table_list.first;
+	     table_list;
+	     table_list= table_list->next, tablenr++)
 	{
-	  thd->lex.current_select= lex_select_save;
-	  DBUG_RETURN(res);
+	  if (table_list->shared)
+	  {
+	    /*
+	      review notes: Check it carefully. I still can't understand
+	      why I should not touch table->used_keys. For my point of
+	      view we should do here same procedura as it was done by
+	      setup_table
+	    */
+	    DBUG_PRINT("SUBS", ("shared %s", table_list->real_name));
+	    TABLE *table= table_list->table;
+	    table->used_fields=0;
+	    table->const_table=0;
+	    table->outer_join=table->null_row=0;
+	    table->status=STATUS_NO_RECORD;
+	    table->keys_in_use_for_query= table->keys_in_use;
+	    table->maybe_null=test(table->outer_join=table_list->outer_join);
+	    table->tablenr=tablenr;
+	    table->map= (table_map) 1 << tablenr;
+	    table->force_index= table_list->force_index;
+	  }
 	}
 	res= sl->join->optimize();
       }
@@ -334,6 +337,7 @@ int st_select_lex_unit::exec()
     if (!thd->is_fatal_error)			// Check if EOM
     {
       SELECT_LEX *fake_select  = new SELECT_LEX(&thd->lex);
+      fake_select->fake_select= 1;
       offset_limit_cnt= (select_cursor->braces ?
 			 global_parameters->offset_limit : 0);
       select_limit_cnt= (select_cursor->braces ?

sql/sql_yacc.yy

@@ -5003,7 +5003,9 @@ subselect_start:
 	{
 	  LEX *lex=Lex;
 	  if (((int)lex->sql_command >= (int)SQLCOM_HA_OPEN &&
-	       lex->sql_command <= (int)SQLCOM_HA_READ) || lex->sql_command == (int)SQLCOM_KILL)	  {	
+	       lex->sql_command <= (int)SQLCOM_HA_READ) ||
+	       lex->sql_command == (int)SQLCOM_KILL)
+	  {	
 	    send_error(lex->thd, ER_SYNTAX_ERROR);
 	    YYABORT;
 	  }

sql/table.h

@@ -163,15 +163,8 @@ typedef struct st_table_list
   struct st_table_list *natural_join;	/* natural join on this table*/
   /* ... join ... USE INDEX ... IGNORE INDEX */
   List<String>	*use_index, *ignore_index; 
-  /*
-    Usually hold reference on opened table, but may hold reference
-    to node of complete list of tables used in UNION & subselect.
-  */
-  union
-  {
-    TABLE          *table;      /* opened table */
-    st_table_list  *table_list; /* pointer to node of list of all tables */
-  };
+  TABLE          *table;      /* opened table */
+  st_table_list  *table_list; /* pointer to node of list of all tables */
   class st_select_lex_unit *derived;	/* SELECT_LEX_UNIT of derived table */
  GRANT_INFO	grant;
   thr_lock_type lock_type;