fixed bugs in temporary tables in subselect implementation (SCRUM)

merging with switching on static tables optimization (SCRUM)
fixed subselects with uncacheable results
added test for fixed bugs from bugreports


mysql-test/r/subselect.result:
  changes in subselect test after switching on static tables optimization
  fixed bug test added
  uncacheable subselects
mysql-test/t/subselect.test:
  changes in subselect test after switching on static tables optimization
  fixed bug test added
  uncacheable subselects
sql/item_create.cc:
  fixed subselects with uncacheable results
sql/item_func.cc:
  fixed subselects with uncacheable results
sql/item_subselect.cc:
  fixed subselects with uncacheable results
  clean up
sql/item_subselect.h:
  fixed subselects with uncacheable results
sql/sql_lex.cc:
  fixed subselects with uncacheable results
sql/sql_lex.h:
  fixed subselects with uncacheable results
sql/sql_select.cc:
  fixed bugs in temporary tables in subselect implementation
  fixed subselects with uncacheable results
sql/sql_union.cc:
  fixed subselects with uncacheable results
sql/sql_yacc.yy:
  fixed subselects with uncacheable results

mysql-test/r/subselect.result

@@ -278,7 +278,7 @@ NULL	1
 explain select (select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a), a from t2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	
-2	DEPENDENT SUBSELECT	t1	system	NULL	NULL	NULL	NULL	1	Using where
+2	DEPENDENT SUBSELECT	t1	system	NULL	NULL	NULL	NULL	1	
 3	DEPENDENT UNION	t5	ALL	NULL	NULL	NULL	NULL	2	Using where
 select (select a from t1 where t1.a=t2.a union all select a from t5 where t5.a=t2.a), a from t2;
 Subselect returns more than 1 record
@@ -321,9 +321,9 @@ INSERT INTO t8 (pseudo,email) VALUES ('2joce1','2test1');
 EXPLAIN SELECT pseudo,(SELECT email FROM t8 WHERE pseudo=(SELECT pseudo FROM t8 WHERE pseudo='joce')) FROM t8 WHERE pseudo=(SELECT pseudo FROM t8 WHERE pseudo='joce');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t8	const	PRIMARY	PRIMARY	35	const	1	
-4	SUBSELECT	t8	const	PRIMARY	PRIMARY	35	const	1	
+4	SUBSELECT	t8	const	PRIMARY	PRIMARY	35		1	
 2	SUBSELECT	t8	const	PRIMARY	PRIMARY	35	const	1	
-3	SUBSELECT	t8	const	PRIMARY	PRIMARY	35	const	1	
+3	SUBSELECT	t8	const	PRIMARY	PRIMARY	35		1	
 SELECT pseudo FROM t8 WHERE pseudo=(SELECT pseudo,email FROM
 t8 WHERE pseudo='joce');
 Cardinality error (more/less than 1 columns)
@@ -397,33 +397,51 @@ SELECT (SELECT 1) as a FROM (SELECT 1 FROM t1 HAVING a=1) b;
 Unknown column 'a' in 'having clause'
 SELECT 1 IN (SELECT 1 FROM t2 HAVING a);
 Unknown column 'a' in 'having clause'
-SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY date);
+SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY topic);
-mot	topic	date	pseudo
-joce	40143	2002-10-22	joce
-SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY date HAVING topic < 4100);
-mot	topic	date	pseudo
-SELECT * from t2 where topic IN (SELECT SUM(topic) FROM t1);
-mot	topic	date	pseudo
-SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY date);
-mot	topic	date	pseudo
-joce	40143	2002-10-22	joce
-SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY date HAVING topic < 4100);
-mot	topic	date	pseudo
-SELECT * from t2 where topic = any (SELECT SUM(topic) FROM t1);
-mot	topic	date	pseudo
-SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY date);
-mot	topic	date	pseudo
-joce	40143	2002-10-22	joce
-SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY date HAVING topic < 4100);
 mot	topic	date	pseudo
 joce	40143	2002-10-22	joce
 joce	43506	2002-10-22	joce
+SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100);
+mot	topic	date	pseudo
+SELECT * from t2 where topic IN (SELECT SUM(topic) FROM t1);
+mot	topic	date	pseudo
+SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY topic);
+mot	topic	date	pseudo
+joce	40143	2002-10-22	joce
+joce	43506	2002-10-22	joce
+SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100);
+mot	topic	date	pseudo
+SELECT * from t2 where topic = any (SELECT SUM(topic) FROM t1);
+mot	topic	date	pseudo
+SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY topic);
+mot	topic	date	pseudo
+SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100);
+mot	topic	date	pseudo
+joce	40143	2002-10-22	joce
+joce	43506	2002-10-22	joce
+SELECT *, topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100) from t2;
+mot	topic	date	pseudo	topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100)
+joce	40143	2002-10-22	joce	1
+joce	43506	2002-10-22	joce	1
 SELECT * from t2 where topic = all (SELECT SUM(topic) FROM t2);
 mot	topic	date	pseudo
 SELECT * from t2 where topic <> any (SELECT SUM(topic) FROM t2);
 mot	topic	date	pseudo
 joce	40143	2002-10-22	joce
 joce	43506	2002-10-22	joce
+SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000);
+mot	topic	date	pseudo
+joce	40143	2002-10-22	joce
+SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000);
+mot	topic	date	pseudo
+joce	40143	2002-10-22	joce
+SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000);
+mot	topic	date	pseudo
+joce	40143	2002-10-22	joce
+SELECT *, topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000) from t2;
+mot	topic	date	pseudo	topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000)
+joce	40143	2002-10-22	joce	1
+joce	43506	2002-10-22	joce	0
 drop table t1,t2;
 CREATE TABLE `t1` (
 `numeropost` mediumint(8) unsigned NOT NULL auto_increment,
@@ -850,3 +868,86 @@ do (SELECT a from t1);
 Table 'test.t1' doesn't exist
 set @a:=(SELECT a from t1);
 Table 'test.t1' doesn't exist
+CREATE TABLE t1 (a int, KEY(a));
+HANDLER t1 OPEN;
+HANDLER t1 READ a=((SELECT 1));
+You have an error in your SQL syntax.  Check the manual that corresponds to your MySQL server version for the right syntax to use
+HANDLER t1 CLOSE;
+drop table t1;
+create table t1 (a int);
+create table t2 (b int);
+insert into t1 values (1),(2);
+insert into t2 values (1);
+select a from t1 where a in (select a from t1 where a in (select b from t2));
+a
+1
+drop table t1, t2;
+create table t1 (a int, b int);
+create table t2 like t1;
+insert into t1 values (1,2),(1,3),(1,4),(1,5);
+insert into t2 values (1,2),(1,3);
+select * from t1 where row(a,b) in (select a,b from t2);
+a	b
+1	2
+1	3
+drop table t1, t2;
+CREATE TABLE `t1` (`i` int(11) NOT NULL default '0',PRIMARY KEY  (`i`)) TYPE=MyISAM CHARSET=latin1;
+INSERT INTO t1 VALUES (1);
+UPDATE t1 SET i=i+1 WHERE i=(SELECT MAX(i));
+Invalid use of group function
+drop table t1;
+CREATE TABLE t (a int(1));
+EXPLAIN SELECT (SELECT RAND() FROM t) FROM t;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t	system	NULL	NULL	NULL	NULL	0	const row not found
+2	UNCACHEABLE SUBSELECT	t	system	NULL	NULL	NULL	NULL	0	const row not found
+EXPLAIN SELECT (SELECT ENCRYPT('test') FROM t) FROM t;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t	system	NULL	NULL	NULL	NULL	0	const row not found
+2	UNCACHEABLE SUBSELECT	t	system	NULL	NULL	NULL	NULL	0	const row not found
+EXPLAIN SELECT (SELECT BENCHMARK(1,1) FROM t) FROM t;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t	system	NULL	NULL	NULL	NULL	0	const row not found
+2	UNCACHEABLE SUBSELECT	t	system	NULL	NULL	NULL	NULL	0	const row not found
+drop table t;
+CREATE TABLE `t1` (
+`mot` varchar(30) character set latin1 NOT NULL default '',
+`topic` mediumint(8) unsigned NOT NULL default '0',
+`date` date NOT NULL default '0000-00-00',
+`pseudo` varchar(35) character set latin1 NOT NULL default '',
+PRIMARY KEY  (`mot`,`pseudo`,`date`,`topic`),
+KEY `pseudo` (`pseudo`,`date`,`topic`),
+KEY `topic` (`topic`)
+) TYPE=MyISAM CHARSET=latin1 ROW_FORMAT=DYNAMIC;
+CREATE TABLE `t2` (
+`mot` varchar(30) character set latin1 NOT NULL default '',
+`topic` mediumint(8) unsigned NOT NULL default '0',
+`date` date NOT NULL default '0000-00-00',
+`pseudo` varchar(35) character set latin1 NOT NULL default '',
+PRIMARY KEY  (`mot`,`pseudo`,`date`,`topic`),
+KEY `pseudo` (`pseudo`,`date`,`topic`),
+KEY `topic` (`topic`)
+) TYPE=MyISAM CHARSET=latin1 ROW_FORMAT=DYNAMIC;
+CREATE TABLE `t3` (
+`numeropost` mediumint(8) unsigned NOT NULL auto_increment,
+`maxnumrep` int(10) unsigned NOT NULL default '0',
+PRIMARY KEY  (`numeropost`),
+UNIQUE KEY `maxnumrep` (`maxnumrep`)
+) TYPE=MyISAM CHARSET=latin1;
+INSERT INTO t1 VALUES ('joce','1','','joce'),('test','2','','test');
+INSERT INTO t2 VALUES ('joce','1','','joce'),('test','2','','test');
+INSERT INTO t3 VALUES (1,1);
+SELECT DISTINCT topic FROM t2 WHERE NOT EXISTS(SELECT * FROM t3 WHERE
+numeropost=topic);
+topic
+2
+select * from t1;
+mot	topic	date	pseudo
+joce	1	0000-00-00	joce
+test	2	0000-00-00	test
+DELETE FROM t1 WHERE topic IN (SELECT DISTINCT topic FROM t2 WHERE NOT
+EXISTS(SELECT * FROM t3 WHERE numeropost=topic));
+select * from t1;
+mot	topic	date	pseudo
+joce	1	0000-00-00	joce
+drop table t1, t2, t3;

mysql-test/t/subselect.test

@@ -215,13 +215,13 @@ SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY topic HAVING t
 SELECT * from t2 where topic = any (SELECT SUM(topic) FROM t1);
 SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY topic);
 SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100);
-SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100;
 SELECT *, topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100) from t2;
 SELECT * from t2 where topic = all (SELECT SUM(topic) FROM t2);
 SELECT * from t2 where topic <> any (SELECT SUM(topic) FROM t2);
-delete from t2 where topic=40143;
+SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000);
-SELECT *, topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100) from t2;
+SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000);
-SELECT *, topic as fff, exists (SELECT topic FROM t2 GROUP BY topic HAVING topic < 4100 and fff = topic) from t2;
+SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000);
+SELECT *, topic = all (SELECT topic FROM t2 GROUP BY topic HAVING topic < 41000) from t2;
 drop table t1,t2;
 
 #forumconthardwarefr7
@@ -483,3 +483,79 @@ drop table t1;
 do (SELECT a from t1);
 -- error 1146
 set @a:=(SELECT a from t1);
+
+CREATE TABLE t1 (a int, KEY(a)); 
+HANDLER t1 OPEN;
+-- error 1149
+HANDLER t1 READ a=((SELECT 1));
+HANDLER t1 CLOSE;
+drop table t1;
+
+create table t1 (a int);
+create table t2 (b int);
+insert into t1 values (1),(2);
+insert into t2 values (1);
+select a from t1 where a in (select a from t1 where a in (select b from t2));
+drop table t1, t2;
+
+create table t1 (a int, b int);
+create table t2 like t1;
+insert into t1 values (1,2),(1,3),(1,4),(1,5);
+insert into t2 values (1,2),(1,3);
+select * from t1 where row(a,b) in (select a,b from t2);
+drop table t1, t2;
+
+CREATE TABLE `t1` (`i` int(11) NOT NULL default '0',PRIMARY KEY  (`i`)) TYPE=MyISAM CHARSET=latin1;
+INSERT INTO t1 VALUES (1);
+-- error 1111
+UPDATE t1 SET i=i+1 WHERE i=(SELECT MAX(i));
+drop table t1;
+
+#test of uncacheable subqueries
+CREATE TABLE t (a int(1));
+EXPLAIN SELECT (SELECT RAND() FROM t) FROM t;
+EXPLAIN SELECT (SELECT ENCRYPT('test') FROM t) FROM t;
+EXPLAIN SELECT (SELECT BENCHMARK(1,1) FROM t) FROM t;
+drop table t;
+
+
+CREATE TABLE `t1` (
+  `mot` varchar(30) character set latin1 NOT NULL default '',
+  `topic` mediumint(8) unsigned NOT NULL default '0',
+  `date` date NOT NULL default '0000-00-00',
+  `pseudo` varchar(35) character set latin1 NOT NULL default '',
+  PRIMARY KEY  (`mot`,`pseudo`,`date`,`topic`),
+  KEY `pseudo` (`pseudo`,`date`,`topic`),
+  KEY `topic` (`topic`)
+) TYPE=MyISAM CHARSET=latin1 ROW_FORMAT=DYNAMIC;
+
+CREATE TABLE `t2` (
+  `mot` varchar(30) character set latin1 NOT NULL default '',
+  `topic` mediumint(8) unsigned NOT NULL default '0',
+  `date` date NOT NULL default '0000-00-00',
+  `pseudo` varchar(35) character set latin1 NOT NULL default '',
+  PRIMARY KEY  (`mot`,`pseudo`,`date`,`topic`),
+  KEY `pseudo` (`pseudo`,`date`,`topic`),
+  KEY `topic` (`topic`)
+) TYPE=MyISAM CHARSET=latin1 ROW_FORMAT=DYNAMIC;
+
+CREATE TABLE `t3` (
+  `numeropost` mediumint(8) unsigned NOT NULL auto_increment,
+  `maxnumrep` int(10) unsigned NOT NULL default '0',
+  PRIMARY KEY  (`numeropost`),
+  UNIQUE KEY `maxnumrep` (`maxnumrep`)
+) TYPE=MyISAM CHARSET=latin1;
+INSERT INTO t1 VALUES ('joce','1','','joce'),('test','2','','test');
+
+INSERT INTO t2 VALUES ('joce','1','','joce'),('test','2','','test');
+
+INSERT INTO t3 VALUES (1,1);
+
+SELECT DISTINCT topic FROM t2 WHERE NOT EXISTS(SELECT * FROM t3 WHERE
+numeropost=topic);
+select * from t1;
+DELETE FROM t1 WHERE topic IN (SELECT DISTINCT topic FROM t2 WHERE NOT
+EXISTS(SELECT * FROM t3 WHERE numeropost=topic));
+select * from t1;
+
+drop table t1, t2, t3;

sql/item_create.cc

@@ -167,7 +167,7 @@ Item *create_func_from_days(Item* a)
 
 Item *create_func_get_lock(Item* a, Item *b)
 {
-  current_thd->lex.safe_to_cache_query=0;
+  current_thd->lex.uncacheable();
   return new Item_func_get_lock(a, b);
 }
 
@@ -327,7 +327,7 @@ Item *create_func_radians(Item *a)
 
 Item *create_func_release_lock(Item* a)
 {
-  current_thd->lex.safe_to_cache_query=0;
+  current_thd->lex.uncacheable();
   return new Item_func_release_lock(a);
 }
 
@@ -435,13 +435,13 @@ Item *create_func_year(Item* a)
 
 Item *create_load_file(Item* a)
 {
-  current_thd->lex.safe_to_cache_query=0;
+  current_thd->lex.uncacheable();
   return new Item_load_file(a);
 }
 
 Item *create_wait_for_master_pos(Item* a, Item* b)
 {
-  current_thd->lex.safe_to_cache_query=0;
+  current_thd->lex.uncacheable();
   return new Item_master_pos_wait(a, b);
 }
 
@@ -463,7 +463,7 @@ Item *create_func_cast(Item *a, Item_cast cast_type)
 
 Item *create_func_is_free_lock(Item* a)
 {
-  current_thd->lex.safe_to_cache_query=0;
+  current_thd->lex.uncacheable();
   return new Item_func_is_free_lock(a);
 }
 

sql/item_func.cc

@@ -2544,7 +2544,7 @@ Item *get_system_var(enum_var_type var_type, LEX_STRING name)
   }
   if (!(item=var->item(thd, var_type)))
     return 0;					// Impossible
-  thd->lex.safe_to_cache_query=0;
+  thd->lex.uncacheable();
   buff[0]='@';
   buff[1]='@';
   pos=buff+2;
@@ -2570,7 +2570,7 @@ Item *get_system_var(enum_var_type var_type, const char *var_name, uint length,
   DBUG_ASSERT(var != 0);
   if (!(item=var->item(thd, var_type)))
     return 0;					// Impossible
-  thd->lex.safe_to_cache_query=0;
+  thd->lex.uncacheable();
   item->set_name(item_name);		// Will use original name
   return item;
 }

sql/item_subselect.cc

@@ -129,7 +129,8 @@ void Item_subselect::fix_length_and_dec()
 
 inline table_map Item_subselect::used_tables() const
 {
-  return (table_map) engine->depended() ? 1L : 0L; 
+  return (table_map) (engine->dependent() ? 1L :
+		      (engine->uncacheable() ? RAND_TABLE_BIT : 0L));
 }
 
 Item_singlerow_subselect::Item_singlerow_subselect(THD *thd,
@@ -795,7 +796,7 @@ int subselect_single_select_engine::exec()
       DBUG_RETURN(join->error?join->error:1);
     }
   }
-  if (select_lex->dependent && executed)
+  if ((select_lex->dependent || select_lex->uncacheable) && executed)
   {
     if (join->reinit())
     {
@@ -837,16 +838,26 @@ uint subselect_union_engine::cols()
   return unit->first_select()->item_list.elements;
 }
 
-bool subselect_single_select_engine::depended()
+bool subselect_single_select_engine::dependent()
 {
   return select_lex->dependent;
 }
 
-bool subselect_union_engine::depended()
+bool subselect_union_engine::dependent()
 {
   return unit->dependent;
 }
 
+bool subselect_single_select_engine::uncacheable()
+{
+  return select_lex->uncacheable;
+}
+
+bool subselect_union_engine::uncacheable()
+{
+  return unit->uncacheable;
+}
+
 bool subselect_single_select_engine::check_loop(uint id)
 {
   DBUG_ENTER("subselect_single_select_engine::check_loop");
@@ -865,13 +876,9 @@ bool subselect_union_engine::check_loop(uint id)
 void subselect_single_select_engine::exclude()
 {
   select_lex->master_unit()->exclude_level();
-  //if (current_thd->lex->describe)
 }
 
 void subselect_union_engine::exclude()
 {
   unit->exclude_level();
-  // for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
-  //  if (sl->join && sl->join->check_loop(id))
-  //    DBUG_RETURN(1);
 }

sql/item_subselect.h

@@ -223,7 +223,8 @@ public:
   virtual void fix_length_and_dec(Item_cache** row)= 0;
   virtual int exec()= 0;
   virtual uint cols()= 0; /* return number of columnss in select */
-  virtual bool depended()= 0; /* depended from outer select */
+  virtual bool dependent()= 0; /* depended from outer select */
+  virtual bool uncacheable()= 0; /* query is uncacheable */
   enum Item_result type() { return res_type; }
   virtual bool check_loop(uint id)= 0;
   virtual void exclude()= 0;
@@ -245,7 +246,8 @@ public:
   void fix_length_and_dec(Item_cache** row);
   int exec();
   uint cols();
-  bool depended();
+  bool dependent();
+  bool uncacheable();
   bool check_loop(uint id);
   void exclude();
 };
@@ -262,7 +264,8 @@ public:
   void fix_length_and_dec(Item_cache** row);
   int exec();
   uint cols();
-  bool depended();
+  bool dependent();
+  bool uncacheable();
   bool check_loop(uint id);
   void exclude();
 };

sql/sql_lex.cc

@@ -995,7 +995,7 @@ int yylex(void *arg, void *yythd)
 
 void st_select_lex_node::init_query()
 {
-  no_table_names_allowed= dependent= 0;
+  no_table_names_allowed= uncacheable= dependent= 0;
   ref_pointer_array= 0;
 }
 

sql/sql_lex.h

@@ -216,6 +216,7 @@ public:
   uint with_sum_func;   /* sum function indicator and number of it */
   bool create_refs;
   bool dependent;	/* dependent from outer select subselect */
+  bool uncacheable;     /* result of this query can't be cached */
   bool no_table_names_allowed; /* used for global order by */
 
   static void *operator new(size_t size)
@@ -475,6 +476,13 @@ typedef struct st_lex
   CHARSET_INFO *charset;
   char *help_arg;
   bool tmp_table_used;
+
+  inline void uncacheable()
+  {
+    safe_to_cache_query= 0;
+    current_select->uncacheable = 
+      current_select->master_unit()->uncacheable= 1;
+  }
 } LEX;
 
 

sql/sql_select.cc

@@ -839,7 +839,6 @@ JOIN::reinit()
     exec_tmp_table1->file->extra(HA_EXTRA_RESET_STATE);
     exec_tmp_table1->file->delete_all_rows();
     free_io_cache(exec_tmp_table1);
-    memcpy(ref_pointer_array, items0, ref_pointer_array_size);
   }
   if (exec_tmp_table2)
   {
@@ -850,9 +849,6 @@ JOIN::reinit()
   if (items0)
     memcpy(ref_pointer_array, items0, ref_pointer_array_size);
 
-  tmp_table_param.copy_funcs.empty();
-  tmp_table_param.copy_field= tmp_table_param.copy_field_end= 0;
-
   if (tmp_join)
     restore_tmp();
 
@@ -4824,7 +4820,7 @@ bool create_myisam_from_heap(THD *thd, TABLE *table, TMP_TABLE_PARAM *param,
 static int
 do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
 {
-  int error;
+  int error= 0;
   JOIN_TAB *join_tab;
   int (*end_select)(JOIN *, struct st_join_table *,bool);
   DBUG_ENTER("do_select");
@@ -8032,8 +8028,10 @@ int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit, select_result *result)
 				((sl->linkage == DERIVED_TABLE_TYPE) ?
 				 "DERIVED":
 				((sl->dependent)?"DEPENDENT SUBSELECT":
-				 "SUBSELECT")):
+				 (sl->uncacheable?"UNCACHEABLE SUBSELECT":
+				   "SUBSELECT"))):
 				((sl->dependent)?"DEPENDENT UNION":
+				 sl->uncacheable?"UNCACHEABLE UNION":
 				  "UNION"))),
 			      result);
     if (res)

sql/sql_union.cc

@@ -207,11 +207,11 @@ int st_select_lex_unit::exec()
   DBUG_ENTER("st_select_lex_unit::exec");
   SELECT_LEX_NODE *lex_select_save= thd->lex.current_select;
   
-  if (executed && !dependent)
+  if (executed && !(dependent||uncacheable))
     DBUG_RETURN(0);
   executed= 1;
   
-  if (dependent || !item || !item->assigned())
+  if ((dependent||uncacheable) || !item || !item->assigned())
   {
     if (optimized && item && item->assigned())
     {

sql/sql_yacc.yy

@@ -1798,7 +1798,7 @@ select_option:
 	      YYABORT;
 	    Select->options|= OPTION_FOUND_ROWS;
 	  }
-	| SQL_NO_CACHE_SYM { Lex->safe_to_cache_query=0; }
+	| SQL_NO_CACHE_SYM { Lex->uncacheable();; }
 	| SQL_CACHE_SYM    { Select->options|= OPTION_TO_QUERY_CACHE; }
 	| ALL		{}
 	;
@@ -2045,12 +2045,12 @@ simple_expr:
 	| '@' ident_or_text SET_VAR expr
 	  {
 	    $$= new Item_func_set_user_var($2,$4);
-	    Lex->safe_to_cache_query=0;
+	    Lex->uncacheable();;
 	  }
 	| '@' ident_or_text
 	  {
 	    $$= new Item_func_get_user_var($2);
-	    Lex->safe_to_cache_query=0;
+	    Lex->uncacheable();;
 	  }
 	| '@' '@' opt_var_ident_type ident_or_text
 	  {
@@ -2136,7 +2136,7 @@ simple_expr:
 	| ENCRYPT '(' expr ')'
 	  {
 	    $$= new Item_func_encrypt($3);
-	    Lex->safe_to_cache_query=0;
+	    Lex->uncacheable();;
 	  }
 	| ENCRYPT '(' expr ',' expr ')'   { $$= new Item_func_encrypt($3,$5); }
 	| DECODE_SYM '(' expr ',' TEXT_STRING ')'
@@ -2192,6 +2192,7 @@ simple_expr:
 	  {
     	    $$= get_system_var(OPT_SESSION, "last_insert_id", 14,
 			      "last_insert_id()");
+	    Lex->safe_to_cache_query= 0;
 	  }
 	| LAST_INSERT_ID '(' expr ')'
 	  {
@@ -2272,9 +2273,9 @@ simple_expr:
 	| POSITION_SYM '(' no_in_expr IN_SYM expr ')'
 	  { $$ = new Item_func_locate($5,$3); }
 	| RAND '(' expr ')'
-	  { $$= new Item_func_rand($3); Lex->safe_to_cache_query=0;}
+	  { $$= new Item_func_rand($3); Lex->uncacheable();}
 	| RAND '(' ')'
-	  { $$= new Item_func_rand(); Lex->safe_to_cache_query=0;}
+	  { $$= new Item_func_rand(); Lex->uncacheable();}
 	| REPLACE '(' expr ',' expr ',' expr ')'
 	  { $$= new Item_func_replace($3,$5,$7); }
 	| RIGHT '(' expr ',' expr ')'
@@ -2376,7 +2377,7 @@ simple_expr:
 	| BENCHMARK_SYM '(' ULONG_NUM ',' expr ')'
 	  {
 	    $$=new Item_func_benchmark($3,$5);
-	    Lex->safe_to_cache_query=0;
+	    Lex->uncacheable();
 	  }
 	| EXTRACT_SYM '(' interval FROM expr ')'
 	{ $$=new Item_extract( $3, $5); };
@@ -2874,7 +2875,7 @@ procedure_clause:
 	    lex->proc_list.next= (byte**) &lex->proc_list.first;
 	    if (add_proc_to_list(lex->thd, new Item_field(NULL,NULL,$2.str)))
 	      YYABORT;
-	    Lex->safe_to_cache_query=0;
+	    Lex->uncacheable();
 	  }
 	  '(' procedure_list ')';
 
@@ -2948,7 +2949,7 @@ into:
 	}
         | INTO select_var_list_init
 	{
-	  Lex->safe_to_cache_query=0;
+	  Lex->uncacheable();
 	}
         ;