fixed support of used_tables() and const_item() in subqueries

(BUG#1444)

mysql-test/r/subselect.result

@@ -1439,3 +1439,21 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	3	Using where
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
 drop table if exists t2, t3;
+CREATE TABLE `t1` ( `id` mediumint(9) NOT NULL auto_increment, `taskid` bigint(20) NOT NULL default '0', `dbid` int(11) NOT NULL default '0', `create_date` datetime NOT NULL default '0000-00-00 00:00:00', `last_update` datetime NOT NULL default '0000-00-00 00:00:00', PRIMARY KEY  (`id`)) TYPE=MyISAM CHARSET=latin1 AUTO_INCREMENT=3 ;
+INSERT INTO `t1` (`id`, `taskid`, `dbid`, `create_date`,`last_update`) VALUES (1, 1, 15, '2003-09-29 10:31:36', '2003-09-29 10:31:36'), (2, 1, 21, now(), now());
+CREATE TABLE `t2` (`db_id` int(11) NOT NULL auto_increment,`name` varchar(200) NOT NULL default '',`primary_uid` smallint(6) NOT NULL default '0',`secondary_uid` smallint(6) NOT NULL default '0',PRIMARY KEY  (`db_id`),UNIQUE KEY `name_2` (`name`),FULLTEXT KEY `name` (`name`)) TYPE=MyISAM CHARSET=latin1 AUTO_INCREMENT=2147483647;
+INSERT INTO `t2` (`db_id`, `name`, `primary_uid`, `secondary_uid`) VALUES (18, 'Not Set 1', 0, 0),(19, 'Valid', 1, 2),(20, 'Valid 2', 1, 2),(21, 'Should Not Return', 1, 2),(26, 'Not Set 2', 0, 0),(-1, 'ALL DB\'S', 0, 0);
+CREATE TABLE `t3` (`taskgenid` mediumint(9) NOT NULL auto_increment,`dbid` int(11) NOT NULL default '0',`taskid` int(11) NOT NULL default '0',`mon` tinyint(4) NOT NULL default '1',`tues` tinyint(4) NOT NULL default '1',`wed` tinyint(4) NOT NULL default '1',`thur` tinyint(4) NOT NULL default '1',`fri` tinyint(4) NOT NULL default '1',`sat` tinyint(4) NOT NULL default '0',`sun` tinyint(4) NOT NULL default '0',`how_often` smallint(6) NOT NULL default '1',`userid` smallint(6) NOT NULL default '0',`active` tinyint(4) NOT NULL default '1',PRIMARY KEY  (`taskgenid`)) TYPE=MyISAM CHARSET=latin1 AUTO_INCREMENT=2 ;
+INSERT INTO `t3` (`taskgenid`, `dbid`, `taskid`, `mon`, `tues`,`wed`, `thur`, `fri`, `sat`, `sun`, `how_often`, `userid`, `active`) VALUES (1,-1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1);
+CREATE TABLE `t4` (`task_id` smallint(6) NOT NULL default '0',`description` varchar(200) NOT NULL default '') TYPE=MyISAM CHARSET=latin1;
+INSERT INTO `t4` (`task_id`, `description`) VALUES (1, 'Daily Check List'),(2, 'Weekly Status');
+select  dbid, name, (date_format(now() , '%Y-%m-%d') - INTERVAL how_often DAY) >= ifnull((SELECT date_format(max(create_date),'%Y-%m-%d') FROM t1 WHERE dbid = b.db_id AND taskid = a.taskgenid), '1950-01-01') from t3 a, t2 b, t4  WHERE dbid = - 1 AND primary_uid = '1' AND t4.task_id = taskid;
+dbid	name	(date_format(now() , '%Y-%m-%d') - INTERVAL how_often DAY) >= ifnull((SELECT date_format(max(create_date),'%Y-%m-%d') FROM t1 WHERE dbid = b.db_id AND taskid = a.taskgenid), '1950-01-01')
+-1	Valid	1
+-1	Valid 2	1
+-1	Should Not Return	0
+SELECT dbid, name FROM t3 a, t2 b, t4 WHERE dbid = - 1 AND primary_uid = '1' AND ((date_format(now() , '%Y-%m-%d') - INTERVAL how_often DAY) >= ifnull((SELECT date_format(max(create_date),'%Y-%m-%d') FROM t1 WHERE dbid = b.db_id AND taskid = a.taskgenid), '1950-01-01')) AND t4.task_id = taskid;
+dbid	name
+-1	Valid
+-1	Valid 2
+drop table t1,t2,t3,t4;

mysql-test/t/subselect.test

@@ -965,3 +965,19 @@ insert into t2 values (2,2), (2,1), (3,3), (3,1);
 select * from t3 where a > all (select max(b) from t2 group by a);
 explain select * from t3 where a > all (select max(b) from t2 group by a);
 drop table if exists t2, t3;
+
+#
+# correct used_tables()
+#
+
+CREATE TABLE `t1` ( `id` mediumint(9) NOT NULL auto_increment, `taskid` bigint(20) NOT NULL default '0', `dbid` int(11) NOT NULL default '0', `create_date` datetime NOT NULL default '0000-00-00 00:00:00', `last_update` datetime NOT NULL default '0000-00-00 00:00:00', PRIMARY KEY  (`id`)) TYPE=MyISAM CHARSET=latin1 AUTO_INCREMENT=3 ;
+INSERT INTO `t1` (`id`, `taskid`, `dbid`, `create_date`,`last_update`) VALUES (1, 1, 15, '2003-09-29 10:31:36', '2003-09-29 10:31:36'), (2, 1, 21, now(), now());
+CREATE TABLE `t2` (`db_id` int(11) NOT NULL auto_increment,`name` varchar(200) NOT NULL default '',`primary_uid` smallint(6) NOT NULL default '0',`secondary_uid` smallint(6) NOT NULL default '0',PRIMARY KEY  (`db_id`),UNIQUE KEY `name_2` (`name`),FULLTEXT KEY `name` (`name`)) TYPE=MyISAM CHARSET=latin1 AUTO_INCREMENT=2147483647;
+INSERT INTO `t2` (`db_id`, `name`, `primary_uid`, `secondary_uid`) VALUES (18, 'Not Set 1', 0, 0),(19, 'Valid', 1, 2),(20, 'Valid 2', 1, 2),(21, 'Should Not Return', 1, 2),(26, 'Not Set 2', 0, 0),(-1, 'ALL DB\'S', 0, 0);
+CREATE TABLE `t3` (`taskgenid` mediumint(9) NOT NULL auto_increment,`dbid` int(11) NOT NULL default '0',`taskid` int(11) NOT NULL default '0',`mon` tinyint(4) NOT NULL default '1',`tues` tinyint(4) NOT NULL default '1',`wed` tinyint(4) NOT NULL default '1',`thur` tinyint(4) NOT NULL default '1',`fri` tinyint(4) NOT NULL default '1',`sat` tinyint(4) NOT NULL default '0',`sun` tinyint(4) NOT NULL default '0',`how_often` smallint(6) NOT NULL default '1',`userid` smallint(6) NOT NULL default '0',`active` tinyint(4) NOT NULL default '1',PRIMARY KEY  (`taskgenid`)) TYPE=MyISAM CHARSET=latin1 AUTO_INCREMENT=2 ;
+INSERT INTO `t3` (`taskgenid`, `dbid`, `taskid`, `mon`, `tues`,`wed`, `thur`, `fri`, `sat`, `sun`, `how_often`, `userid`, `active`) VALUES (1,-1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1);
+CREATE TABLE `t4` (`task_id` smallint(6) NOT NULL default '0',`description` varchar(200) NOT NULL default '') TYPE=MyISAM CHARSET=latin1;
+INSERT INTO `t4` (`task_id`, `description`) VALUES (1, 'Daily Check List'),(2, 'Weekly Status');
+select  dbid, name, (date_format(now() , '%Y-%m-%d') - INTERVAL how_often DAY) >= ifnull((SELECT date_format(max(create_date),'%Y-%m-%d') FROM t1 WHERE dbid = b.db_id AND taskid = a.taskgenid), '1950-01-01') from t3 a, t2 b, t4  WHERE dbid = - 1 AND primary_uid = '1' AND t4.task_id = taskid;
+SELECT dbid, name FROM t3 a, t2 b, t4 WHERE dbid = - 1 AND primary_uid = '1' AND ((date_format(now() , '%Y-%m-%d') - INTERVAL how_often DAY) >= ifnull((SELECT date_format(max(create_date),'%Y-%m-%d') FROM t1 WHERE dbid = b.db_id AND taskid = a.taskgenid), '1950-01-01')) AND t4.task_id = taskid;
+drop table t1,t2,t3,t4;

sql/item.cc

@@ -817,9 +817,11 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
       // Prevent using outer fields in subselects, that is not supported now
       SELECT_LEX *cursel=(SELECT_LEX *) thd->lex.current_select;
       if (cursel->master_unit()->first_select()->linkage != DERIVED_TABLE_TYPE)
-	for (SELECT_LEX *sl= cursel->outer_select();
+      {
+	SELECT_LEX_UNIT *prev_unit= cursel->master_unit();
+	for (SELECT_LEX *sl= prev_unit->outer_select();
 	     sl;
-	     sl= sl->outer_select())
+	     sl= (prev_unit= sl->master_unit())->outer_select())
 	{
 	  table_list= (last= sl)->get_table_list();
 	  if (sl->resolve_mode == SELECT_LEX::INSERT_MODE && table_list)
@@ -830,16 +832,33 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 	  if ((tmp= find_field_in_tables(thd, this,
 					 table_list, &where,
 					 0)) != not_found_field)
+	  {
+	    prev_unit->item->used_tables_cache|= tmp->table->map;
+	    prev_unit->item->const_item_cache= 0;
 	    break;
+	  }
 	  if (sl->resolve_mode == SELECT_LEX::SELECT_MODE &&
 	      (refer= find_item_in_list(this, sl->item_list, &counter, 
 					 REPORT_EXCEPT_NOT_FOUND)) != 
 	       (Item **) not_found_item)
+	  {
+	    if (*refer && (*refer)->fixed) // Avoid crash in case of error
+	    {
+	      prev_unit->item->used_tables_cache|= (*refer)->used_tables();
+	      prev_unit->item->const_item_cache&= (*refer)->const_item();
+	    }
 	    break;
+	  }
+
+	  // Reference is not found => depend from outer (or just error)
+	  prev_unit->item->used_tables_cache|= OUTER_REF_TABLE_BIT;
+	  prev_unit->item->const_item_cache= 0;
+
 	  if (sl->master_unit()->first_select()->linkage ==
 	      DERIVED_TABLE_TYPE)
 	    break; // do not look over derived table
 	}
+      }
       if (!tmp)
 	return -1;
       else if (!refer)
@@ -1350,7 +1369,8 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
   if (!ref)
   {
     TABLE_LIST *where= 0, *table_list;
-    SELECT_LEX *sl= thd->lex.current_select->outer_select();
+    SELECT_LEX_UNIT *prev_unit= thd->lex.current_select->master_unit();
+    SELECT_LEX *sl= prev_unit->outer_select();
     /*
       Finding only in current select will be performed for selects that have 
       not outer one and for derived tables (which not support using outer 
@@ -1378,7 +1398,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	cause error ER_NON_UNIQ_ERROR in find_item_in_list.
       */
       SELECT_LEX *last=0;
-      for ( ; sl ; sl= sl->outer_select())
+      for ( ; sl ; sl= (prev_unit= sl->master_unit())->outer_select())
       {
 	last= sl;
 	if (sl->resolve_mode == SELECT_LEX::SELECT_MODE &&
@@ -1386,7 +1406,14 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 				    &counter,
 				    REPORT_EXCEPT_NOT_FOUND)) !=
 	   (Item **)not_found_item)
+	{
+	  if (*ref && (*ref)->fixed) // Avoid crash in case of error
+	  {
+	    prev_unit->item->used_tables_cache|= (*ref)->used_tables();
+	    prev_unit->item->const_item_cache&= (*ref)->const_item();
+	  }
 	  break;
+	}
 	table_list= sl->get_table_list();
 	if (sl->resolve_mode == SELECT_LEX::INSERT_MODE && table_list)
 	{
@@ -1396,7 +1423,16 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	if ((tmp= find_field_in_tables(thd, this,
 				       table_list, &where,
 				       0)) != not_found_field)
+	{
+	  prev_unit->item->used_tables_cache|= tmp->table->map;
+	  prev_unit->item->const_item_cache= 0;
 	  break;
+	}
+
+	// Reference is not found => depend from outer (or just error)
+	prev_unit->item->used_tables_cache|= OUTER_REF_TABLE_BIT;
+	prev_unit->item->const_item_cache= 0;
+
 	if (sl->master_unit()->first_select()->linkage ==
 	    DERIVED_TABLE_TYPE)
 	  break; // do not look over derived table

sql/item_subselect.cc

@@ -36,7 +36,8 @@ inline Item * and_items(Item* cond, Item *item)
 
 Item_subselect::Item_subselect():
   Item_result_field(), engine_owner(1), value_assigned(0), substitution(0),
-  engine(0), have_to_be_excluded(0), engine_changed(0)
+  engine(0), used_tables_cache(0), have_to_be_excluded(0),
+  const_item_cache(1), engine_changed(0)
 {
   reset();
   /*
@@ -146,12 +147,27 @@ void Item_subselect::fix_length_and_dec()
   engine->fix_length_and_dec(0);
 }
 
-inline table_map Item_subselect::used_tables() const
+table_map Item_subselect::used_tables() const
 {
-  return (table_map) (engine->dependent() ? 1L :
+  return (table_map) (engine->dependent() ? used_tables_cache :
 		      (engine->uncacheable() ? RAND_TABLE_BIT : 0L));
 }
 
+bool Item_subselect::const_item() const
+{
+  return engine->uncacheable()? 0 : const_item_cache;
+}
+
+void Item_subselect::update_used_tables()
+{
+  if (!engine->uncacheable())
+  {
+    // did all used tables become ststic?
+    if ((used_tables_cache & ~engine->upper_select_const_tables()) == 0)
+      const_item_cache= 1;
+  }
+}
+
 Item_singlerow_subselect::Item_singlerow_subselect(st_select_lex *select_lex)
   :Item_subselect(), value(0)
 {
@@ -1138,3 +1154,29 @@ void subselect_uniquesubquery_engine::exclude()
   //this never should be called
   DBUG_ASSERT(0);
 }
+
+
+table_map subselect_engine::calc_const_tables(TABLE_LIST *table)
+{
+  table_map map= 0;
+  for(; table; table= table->next)
+  {
+    TABLE *tbl= table->table;
+    if (tbl && tbl->const_table)
+      map|= tbl->map;
+  }
+  return map;
+}
+
+
+table_map subselect_single_select_engine::upper_select_const_tables()
+{
+  return calc_const_tables((TABLE_LIST *) select_lex->outer_select()->
+			   table_list.first);
+}
+
+table_map subselect_union_engine::upper_select_const_tables()
+{
+  return calc_const_tables((TABLE_LIST *) unit->outer_select()->
+			   table_list.first);
+}

sql/item_subselect.h

@@ -41,11 +41,15 @@ protected:
   /* substitution instead of subselect in case of optimization */
   Item *substitution;
   /* engine that perform execution of subselect (single select or union) */
-  subselect_engine *engine; 
+  subselect_engine *engine;
+  /* cache of used external tables */
+  table_map used_tables_cache; 
   /* allowed number of columns (1 for single value subqueries) */
   uint max_columns;
   /* work with 'substitution' */
   bool have_to_be_excluded;
+  /* cache of constante state */
+  bool const_item_cache;
 
 public:
   /* changed engine indicator */
@@ -85,6 +89,8 @@ public:
   bool exec();
   virtual void fix_length_and_dec();
   table_map used_tables() const;
+  bool const_item() const;
+  void update_used_tables();
   void print(String *str)
   {
     if (name)
@@ -101,6 +107,8 @@ public:
 
   friend class select_subselect;
   friend class Item_in_optimizer;
+  friend bool Item_field::fix_fields(THD *, TABLE_LIST *, Item **);
+  friend bool Item_ref::fix_fields(THD *, TABLE_LIST *, Item **);
 };
 
 /* single value subselect */
@@ -264,6 +272,8 @@ public:
   enum Item_result type() { return res_type; }
   virtual void exclude()= 0;
   bool may_be_null() { return maybe_null; };
+  virtual table_map upper_select_const_tables()= 0;
+  static table_map calc_const_tables(TABLE_LIST *);
 };
 
 
@@ -285,6 +295,7 @@ public:
   bool dependent();
   bool uncacheable();
   void exclude();
+  table_map upper_select_const_tables();
 };
 
 
@@ -302,6 +313,7 @@ public:
   bool dependent();
   bool uncacheable();
   void exclude();
+  table_map upper_select_const_tables();
 };
 
 
@@ -328,6 +340,7 @@ public:
   bool dependent() { return 1; }
   bool uncacheable() { return 1; }
   void exclude();
+  table_map upper_select_const_tables() { return 0; }
 };