merge

mysql-test/r/derived.result:
  Auto merged
mysql-test/t/derived.test:
  Auto merged
sql/sql_yacc.yy:
  mergin: new code contain this bug fixing

mysql-test/r/union.result

@@ -88,7 +88,6 @@ explain (select a,b from t1 limit 2)  union all (select a,b from t2 order by a l
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ALL	NULL	NULL	NULL	NULL	4	
 t2	ALL	NULL	NULL	NULL	NULL	4	Using filesort
-t1	ALL	NULL	NULL	NULL	NULL	4	
 (select sql_calc_found_rows  a,b from t1 limit 2)  union all (select a,b from t2 order by a) limit 2;
 a	b
 1	a

sql/item_sum.cc

@@ -940,6 +940,7 @@ bool Item_sum_count_distinct::fix_fields(THD *thd,TABLE_LIST *tables)
 bool Item_sum_count_distinct::setup(THD *thd)
 {
   List<Item> list;
+  SELECT_LEX *select_lex= current_lex->select;
   /* Create a table with an unique key over all parameters */
   for (uint i=0; i < arg_count ; i++)
   {
@@ -961,9 +962,10 @@ bool Item_sum_count_distinct::setup(THD *thd)
     free_tmp_table(thd, table);
     tmp_table_param->cleanup();
   }
-  if (!(table=create_tmp_table(thd, tmp_table_param, list, (ORDER*) 0, 1,
-			       0, 0,
-			       current_lex->select->options | thd->options)))
+  if (!(table= create_tmp_table(thd, tmp_table_param, list, (ORDER*) 0, 1,
+				0, 0,
+				select_lex->options | thd->options,
+				(SELECT_LEX_UNIT*) select_lex->master)))
     return 1;
   table->file->extra(HA_EXTRA_NO_ROWS);		// Don't update rows
   table->no_rows=1;

sql/mysql_priv.h

@@ -291,7 +291,7 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list);
 bool mysql_change_db(THD *thd,const char *name);
 void mysql_parse(THD *thd,char *inBuf,uint length);
 void mysql_init_select(LEX *lex);
-bool mysql_new_select(LEX *lex);
+bool mysql_new_select(LEX *lex, bool move_down);
 void mysql_init_multi_delete(LEX *lex);
 void init_max_user_conn(void);
 void free_max_user_conn(void);
@@ -359,9 +359,10 @@ int setup_order(THD *thd,TABLE_LIST *tables, List<Item> &fields,
 int handle_select(THD *thd, LEX *lex, select_result *result);
 int mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &list,COND *conds,
 		 ORDER *order, ORDER *group,Item *having,ORDER *proc_param,
-		 ulong select_type,select_result *result);
-int mysql_union(THD *thd,LEX *lex,select_result *result);
-int mysql_derived(THD *thd,LEX *lex,SELECT_LEX *s, TABLE_LIST *t);
+		 ulong select_type,select_result *result,
+		 SELECT_LEX_UNIT *unit);
+int mysql_union(THD *thd, LEX *lex,select_result *result);
+int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *s, TABLE_LIST *t);
 Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
 			Item_result_field ***copy_func, Field **from_field,
 			bool group,bool modify_item);

sql/sql_class.cc

@@ -389,9 +389,9 @@ bool select_send::send_data(List<Item> &items)
   String *packet= &thd->packet;
   DBUG_ENTER("send_data");
 
-  if (thd->offset_limit)
+  if (unit->offset_limit_cnt)
   {						// using limit offset,count
-    thd->offset_limit--;
+    unit->offset_limit_cnt--;
     DBUG_RETURN(0);
   }
   packet->length(0);				// Reset packet
@@ -439,11 +439,12 @@ select_export::~select_export()
 }
 
 int
-select_export::prepare(List<Item> &list)
+select_export::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
 {
   char path[FN_REFLEN];
   uint option=4;
   bool blob_flag=0;
+  unit= u;
 #ifdef DONT_ALLOW_FULL_LOAD_DATA_PATHS
   option|=1;					// Force use of db directory
 #endif
@@ -510,9 +511,9 @@ bool select_export::send_data(List<Item> &items)
   String tmp(buff,sizeof(buff)),*res;
   tmp.length(0);
 
-  if (thd->offset_limit)
+  if (unit->offset_limit_cnt)
   {						// using limit offset,count
-    thd->offset_limit--;
+    unit->offset_limit_cnt--;
     DBUG_RETURN(0);
   }
   row_count++;
@@ -678,9 +679,11 @@ select_dump::~select_dump()
 }
 
 int
-select_dump::prepare(List<Item> &list __attribute__((unused)))
+select_dump::prepare(List<Item> &list __attribute__((unused)),
+		     SELECT_LEX_UNIT *u)
 {
   uint option=4;
+  unit= u;
 #ifdef DONT_ALLOW_FULL_LOAD_DATA_PATHS
   option|=1;					// Force use of db directory
 #endif
@@ -719,9 +722,9 @@ bool select_dump::send_data(List<Item> &items)
   Item *item;
   DBUG_ENTER("send_data");
 
-  if (thd->offset_limit)
+  if (unit->offset_limit_cnt)
   {						// using limit offset,count
-    thd->offset_limit--;
+    unit->offset_limit_cnt--;
     DBUG_RETURN(0);
   }
   if (row_count++ > 1) 

sql/sql_class.h

@@ -382,7 +382,7 @@ class THD :public ilink {
 #endif  
   ulonglong  next_insert_id,last_insert_id,current_insert_id,
              limit_found_rows;
-  ha_rows    select_limit,offset_limit,default_select_limit,cuted_fields,
+  ha_rows    default_select_limit,cuted_fields,
              max_join_size, sent_row_count, examined_row_count;
   table_map  used_tables;
   UC *user_connect;
@@ -551,10 +551,15 @@ void send_error(NET *net,uint sql_errno=0, const char *err=0);
 class select_result :public Sql_alloc {
 protected:
   THD *thd;
+  SELECT_LEX_UNIT *unit;
 public:
   select_result();
   virtual ~select_result() {};
-  virtual int prepare(List<Item> &list) { return 0; }
+  virtual int prepare(List<Item> &list, SELECT_LEX_UNIT *u)
+  {
+    unit= u;
+    return 0;
+  }
   virtual bool send_fields(List<Item> &list,uint flag)=0;
   virtual bool send_data(List<Item> &items)=0;
   virtual void initialize_tables (JOIN *join=0) {}
@@ -587,7 +592,7 @@ class select_export :public select_result {
 public:
   select_export(sql_exchange *ex) :exchange(ex),file(-1),row_count(0L) {}
   ~select_export();
-  int prepare(List<Item> &list);
+  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_fields(List<Item> &list,
 		   uint flag) { return 0; }
   bool send_data(List<Item> &items);
@@ -606,7 +611,7 @@ class select_dump :public select_result {
   select_dump(sql_exchange *ex) :exchange(ex),file(-1),row_count(0L)
   { path[0]=0; }
   ~select_dump();
-  int prepare(List<Item> &list);
+  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_fields(List<Item> &list,
 		   uint flag) { return 0; }
   bool send_data(List<Item> &items);
@@ -629,7 +634,7 @@ class select_insert :public select_result {
     info.handle_duplicates=duplic;
   }
   ~select_insert();
-  int prepare(List<Item> &list);
+  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_fields(List<Item> &list, uint flag)
   { return 0; }
   bool send_data(List<Item> &items);
@@ -658,7 +663,7 @@ class select_create: public select_insert {
     create_info(create_info_par),
     lock(0)
     {}
-  int prepare(List<Item> &list);
+  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_data(List<Item> &values);
   bool send_eof();
   void abort();
@@ -672,7 +677,7 @@ class select_union :public select_result {
 
   select_union(TABLE *table_par);
   ~select_union();
-  int prepare(List<Item> &list);
+  int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_fields(List<Item> &list, uint flag)
   { return 0; }
   bool send_data(List<Item> &items);
@@ -706,19 +711,28 @@ class Table_ident :public Sql_alloc {
  public:
   LEX_STRING db;
   LEX_STRING table;
-  SELECT_LEX *sel;
-  inline Table_ident(LEX_STRING db_arg,LEX_STRING table_arg,bool force)
-    :table(table_arg), sel((SELECT_LEX *)0)
+  SELECT_LEX_UNIT *sel;
+  inline Table_ident(LEX_STRING db_arg, LEX_STRING table_arg, bool force)
+    :table(table_arg), sel((SELECT_LEX_UNIT *)0)
   {
     if (!force && (current_thd->client_capabilities & CLIENT_NO_SCHEMA))
       db.str=0;
     else
       db= db_arg;
   }
-  inline Table_ident(LEX_STRING table_arg) :table(table_arg), sel((SELECT_LEX *)0) {db.str=0;}
-  inline Table_ident(SELECT_LEX *s) : sel(s) {db.str=0; table.str=(char *)""; table.length=0;}
+  inline Table_ident(LEX_STRING table_arg) 
+    :table(table_arg), sel((SELECT_LEX_UNIT *)0)
+  {
+    db.str=0;
+  }
+  inline Table_ident(SELECT_LEX_UNIT *s) : sel(s) 
+  {
+    db.str=0; table.str=(char *)""; table.length=0;
+  }
   inline void change_db(char *db_name)
-  { db.str= db_name; db.length=(uint) strlen(db_name); }
+  {
+    db.str= db_name; db.length= (uint) strlen(db_name);
+  }
 };
 
 // this is needed for user_vars hash
@@ -778,7 +792,7 @@ class Unique :public Sql_alloc
    multi_delete(THD *thd, TABLE_LIST *dt, thr_lock_type lock_option_arg,
 		uint num_of_tables);
    ~multi_delete();
-   int prepare(List<Item> &list);
+   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
    bool send_fields(List<Item> &list,
  		   uint flag) { return 0; }
    bool send_data(List<Item> &items);
@@ -807,7 +821,7 @@ class Unique :public Sql_alloc
 		enum enum_duplicates handle_duplicates,  
 		thr_lock_type lock_option_arg, uint num);
    ~multi_update();
-   int prepare(List<Item> &list);
+   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
    bool send_fields(List<Item> &list,
  		   uint flag) { return 0; }
    bool send_data(List<Item> &items);

sql/sql_delete.cc

@@ -232,9 +232,10 @@ multi_delete::multi_delete(THD *thd_arg, TABLE_LIST *dt,
 
 
 int
-multi_delete::prepare(List<Item> &values)
+multi_delete::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
 {
   DBUG_ENTER("multi_delete::prepare");
+  unit= u;
   do_delete = true;   
   thd->proc_info="deleting from main table";
 

sql/sql_derived.cc

@@ -28,21 +28,25 @@
 static const char *any_db="*any*";	// Special symbol for check_access
 
 
-int mysql_derived(THD *thd, LEX *lex,SELECT_LEX *s, TABLE_LIST *t)
+int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
 {
-  SELECT_LEX *sl=s;
+  /*
+    TODO: make derived tables with union inside (now only 1 SELECT may be
+    procesed)
+  */
+  SELECT_LEX *sl= (SELECT_LEX*)unit->slave;
   List<Item> item_list;
   TABLE *table;
   int res;
   select_union *derived_result;
-  TABLE_LIST *tables=(TABLE_LIST *)sl->table_list.first;
+  TABLE_LIST *tables= (TABLE_LIST *)sl->table_list.first;
   TMP_TABLE_PARAM tmp_table_param;
   DBUG_ENTER("mysql_derived");
   
   if (tables)
-    res=check_table_access(thd,SELECT_ACL, tables);
+    res= check_table_access(thd,SELECT_ACL, tables);
   else
-    res=check_access(thd, SELECT_ACL, any_db);
+    res= check_access(thd, SELECT_ACL, any_db);
   if (res)
     DBUG_RETURN(-1);
 
@@ -52,7 +56,7 @@ int mysql_derived(THD *thd, LEX *lex,SELECT_LEX *s, TABLE_LIST *t)
   {
     if (cursor->derived)
     {
-      res=mysql_derived(thd,lex,(SELECT_LEX *)cursor->derived,cursor);
+      res=mysql_derived(thd, lex, (SELECT_LEX_UNIT *)cursor->derived, cursor);
       if (res) DBUG_RETURN(res);
     }
   }
@@ -71,9 +75,11 @@ int mysql_derived(THD *thd, LEX *lex,SELECT_LEX *s, TABLE_LIST *t)
     }
     bzero((char*) &tmp_table_param,sizeof(tmp_table_param));
     tmp_table_param.field_count=item_list.elements;
-    if (!(table=create_tmp_table(thd, &tmp_table_param, sl->item_list,
-			       (ORDER*) 0, 0, 1, 0,
-			       (sl->options | thd->options | TMP_TABLE_ALL_COLUMNS))))
+    if (!(table= create_tmp_table(thd, &tmp_table_param, sl->item_list,
+				  (ORDER*) 0, 0, 1, 0,
+				  (sl->options | thd->options | 
+				   TMP_TABLE_ALL_COLUMNS),
+				  unit)))
     {
       res=-1;
       goto exit;
@@ -81,11 +87,11 @@ int mysql_derived(THD *thd, LEX *lex,SELECT_LEX *s, TABLE_LIST *t)
   
     if ((derived_result=new select_union(table)))
     {
-      thd->offset_limit=sl->offset_limit;
-      thd->select_limit=sl->select_limit+sl->offset_limit;
-      if (thd->select_limit < sl->select_limit)
-	thd->select_limit= HA_POS_ERROR;
-      if (thd->select_limit == HA_POS_ERROR)
+      unit->offset_limit_cnt= sl->offset_limit;
+      unit->select_limit_cnt= sl->select_limit+sl->offset_limit;
+      if (unit->select_limit_cnt < sl->select_limit)
+	unit->select_limit_cnt= HA_POS_ERROR;
+      if (unit->select_limit_cnt == HA_POS_ERROR)
 	sl->options&= ~OPTION_FOUND_ROWS;
     
       res=mysql_select(thd, tables,  sl->item_list,
@@ -93,7 +99,7 @@ int mysql_derived(THD *thd, LEX *lex,SELECT_LEX *s, TABLE_LIST *t)
 		       (ORDER*) sl->group_list.first,
 		       sl->having, (ORDER*) NULL,
 		       sl->options | thd->options | SELECT_NO_UNLOCK,
-		       derived_result);
+		       derived_result, unit);
       if (!res)
       {
 // Here we entirely fix both TABLE_LIST and list of SELECT's as there were no derived tables
@@ -103,9 +109,8 @@ int mysql_derived(THD *thd, LEX *lex,SELECT_LEX *s, TABLE_LIST *t)
 	{
 	  t->real_name=table->real_name;
 	  t->table=table;
-	  sl->prev->next=sl->next;
+	  sl->exclude();
 	  t->derived=(SELECT_LEX *)0; // just in case ...
-	  if (!sl->next) lex->last_select = sl;
 	}
       }
       delete derived_result;

sql/sql_insert.cc

@@ -1266,10 +1266,11 @@ bool delayed_insert::handle_inserts(void)
 ***************************************************************************/
 
 int
-select_insert::prepare(List<Item> &values)
+select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
 {
   DBUG_ENTER("select_insert::prepare");
 
+  unit= u;
   save_time_stamp=table->time_stamp;
   if (check_insert_fields(thd,table,*fields,values,1))
     DBUG_RETURN(1);
@@ -1302,9 +1303,9 @@ select_insert::~select_insert()
 
 bool select_insert::send_data(List<Item> &values)
 {
-  if (thd->offset_limit)
+  if (unit->offset_limit_cnt)
   {						// using limit offset,count
-    thd->offset_limit--;
+    unit->offset_limit_cnt--;
     return 0;
   }
   if (fields->elements)
@@ -1380,10 +1381,11 @@ bool select_insert::send_eof()
 ***************************************************************************/
 
 int
-select_create::prepare(List<Item> &values)
+select_create::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
 {
   DBUG_ENTER("select_create::prepare");
 
+  unit= u;
   table=create_table_from_items(thd, create_info, db, name,
 				extra_fields, keys, &values, &lock);
   if (!table)
@@ -1413,9 +1415,9 @@ select_create::prepare(List<Item> &values)
 
 bool select_create::send_data(List<Item> &values)
 {
-  if (thd->offset_limit)
+  if (unit->offset_limit_cnt)
   {						// using limit offset,count
-    thd->offset_limit--;
+    unit->offset_limit_cnt--;
     return 0;
   }
   fill_record(field,values);

sql/sql_lex.cc

@@ -879,3 +879,120 @@ int yylex(void *arg)
     }
   }
 }
+
+/*
+  st_select_lex structures initialisations
+*/
+
+void st_select_lex_node::init_query()
+{
+  next= master= slave= link_next= 0;
+  prev= link_prev= 0;
+}
+
+void st_select_lex_node::init_select()
+{
+  order_list.elements= 0;
+  order_list.first= 0;
+  order_list.next= (byte**) &order_list.first;
+  select_limit= HA_POS_ERROR;
+  offset_limit= 0; 
+}
+
+void st_select_lex_unit::init_query()
+{
+  st_select_lex_node::init_query();
+  global_parameters= this;
+  select_limit_cnt= HA_POS_ERROR;
+  offset_limit_cnt= 0;
+}
+
+void st_select_lex::init_query()
+{
+  st_select_lex_node::init_query();
+  table_list.elements= 0;
+  table_list.first= 0; 
+  table_list.next= (byte**) &table_list.first;
+  item_list.empty();
+}
+
+void st_select_lex::init_select()
+{
+  st_select_lex_node::init_select();
+  group_list.elements= 0;
+  group_list.first= 0;
+  group_list.next= (byte**) &group_list.first;
+  options= 0;
+  where= having= 0;
+  when_list.empty(); 
+  expr_list.empty();
+  interval_list.empty(); 
+  use_index.empty();
+  ftfunc_list.empty();
+  linkage=UNSPECIFIED_TYPE;
+}
+
+/*
+  st_select_lex structures linking
+*/
+
+/* include on level down */
+void st_select_lex_node::include_down(st_select_lex_node *upper)
+{
+  if ((next= upper->slave))
+    next->prev= &next;
+  prev= &upper->slave;
+  upper->slave= this;
+  master= upper;
+}
+
+/* include neighbour (on same level) */
+void st_select_lex_node::include_neighbour(st_select_lex_node *before)
+{
+  if ((next= before->next))
+    next->prev= &next;
+  prev= &before->next;
+  before->next= this;
+  master= before->master;
+}
+
+/* including in global SELECT_LEX list */
+void st_select_lex_node::include_global(st_select_lex_node **plink)
+{
+  if ((link_next= *plink))
+    link_next->link_prev= &link_next;
+  link_prev= plink;
+  *plink= this;
+}
+
+//excluding from global list (internal function)
+void st_select_lex_node::fast_exclude()
+{
+  if(link_prev)
+  {
+    if ((*link_prev= link_next))
+      link_next->link_prev= link_prev;
+    // Remove slave structure
+    for (; slave; slave= slave->next)
+      slave->fast_exclude();
+  }
+}
+
+/*
+  excluding select_lex structure (except first (first select can't be
+  deleted, because it is most upper select))
+*/
+void st_select_lex_node::exclude()
+{
+  //exclude from global list
+  fast_exclude();
+  //exclude from other structures
+  if ((*prev= next))
+    next->prev= prev;
+  /* 
+     We do not need following statements, because prev pointer of first 
+     list element point to master->slave
+     if (master->slave == this)
+       master->slave= next;
+  */
+}

sql/sql_lex.h

@@ -103,28 +103,143 @@ typedef struct st_lex_master_info
 } LEX_MASTER_INFO;
 
 
-enum sub_select_type {UNSPECIFIED_TYPE,UNION_TYPE, INTERSECT_TYPE, EXCEPT_TYPE, NOT_A_SELECT, DERIVED_TABLE_TYPE};
+enum sub_select_type {UNSPECIFIED_TYPE,UNION_TYPE, INTERSECT_TYPE,
+		      EXCEPT_TYPE, GLOBAL_OPTIONS_TYPE, DERIVED_TABLE_TYPE};
 
-/* The state of the lex parsing for selects */
+/* 
+  The state of the lex parsing for selects 
+   
+   All select describing structures linked with following pointers:
+   - list of neighbors (next/prev) (prev of first element point to slave 
+     pointer of upper structure)
+     - one level units for unit (union) structure
+     - member of one union(unit) for ordinary select_lex
+   - pointer to master
+     - outer select_lex for unit (union)
+     - unit structure for ordinary select_lex
+   - pointer to slave
+     - first list element of select_lex belonged to this unit for unit
+     - first unit in list of units that belong to this select_lex (as
+       subselects or derived tables) for ordinary select_lex
+   - list of all select_lex (for group operation like correcting list of opened
+     tables)
+   for example for following query:
 
-typedef struct st_select_lex {
+   select *
+     from table1
+     where table1.field IN (select * from table1_1_1 union
+                            select * from table1_1_2)
+     union
+   select *
+     from table2
+     where table2.field=(select (select f1 from table2_1_1_1_1
+                                   where table2_1_1_1_1.f2=table2_1_1.f3)
+                           from table2_1_1
+                           where table2_1_1.f1=table2.f2)
+     union
+   select * from table3;
+
+   we will have following structure:
+
+
+     main unit
+     select1 select2 select3
+     |^^     |^
+    s|||     ||master
+    l|||     |+---------------------------------+
+    a|||     +---------------------------------+|
+    v|||master                         slave   ||
+    e||+-------------------------+             ||
+     V|            neighbor      |             V|
+     unit 1.1<==================>unit1.2       unit2.1
+     select1.1.1 select 1.1.2    select1.2.1   select2.1.1 select2.1.2
+                                               |^
+                                               ||
+                                               V|
+                                               unit2.1.1.1
+                                               select2.1.1.1.1
+
+
+   relation in main unit will be following:
+                          
+         main unit
+         |^^^
+         ||||
+         |||+------------------------------+
+         ||+--------------+                |
+    slave||master         |                |
+         V|      neighbor |       neighbor |
+         select1<========>select2<========>select3
+
+    list of all select_lex will be following (as it will be constructed by
+    parser):
+
+    select1->select2->select3->select2.1.1->select 2.1.2->select2.1.1.1.1-+
+                                                                          |
+    +---------------------------------------------------------------------+
+    |
+    +->select1.1.1->select1.1.2
+
+*/
+
+/* 
+    Base class for st_select_lex (SELECT_LEX) & 
+    st_select_lex_unit (SELECT_LEX_UNIT)
+*/
+struct st_select_lex_node {
   enum sub_select_type linkage;
-  char *db,*db1,*table1,*db2,*table2;		/* For outer join using .. */
-  Item *where,*having;
-  ha_rows select_limit,offset_limit;
+  st_select_lex_node *next, **prev,   /* neighbor list */
+    *master, *slave,                  /* vertical links */
+    *link_next, **link_prev;          /* list of whole SELECT_LEX */
+  SQL_LIST order_list;                /* ORDER clause */
+  ha_rows select_limit, offset_limit; /* LIMIT clause parameters */
+  void init_query();
+  void init_select();
+  void include_down(st_select_lex_node *upper);
+  void include_neighbour(st_select_lex_node *before);
+  void include_global(st_select_lex_node **plink);
+  void exclude();
+private:
+  void fast_exclude();
+};
+
+/* 
+   SELECT_LEX_UNIT - unit of selects (UNION, INTERSECT, ...) group 
+   SELECT_LEXs
+*/
+struct st_select_lex_unit: public st_select_lex_node {
+  /*
+    Pointer to 'last' select or pointer to unit where stored
+    global parameters for union
+  */
+  st_select_lex_node *global_parameters;
+  /* LIMIT clause runtime counters */
+  ha_rows select_limit_cnt, offset_limit_cnt;
+  void init_query();
+};
+typedef struct st_select_lex_unit SELECT_LEX_UNIT;
+
+/*
+  SELECT_LEX - store information of parsed SELECT_LEX statment
+*/
+struct st_select_lex: public st_select_lex_node {
+  char *db, *db1, *table1, *db2, *table2;      	/* For outer join using .. */
+  Item *where, *having;                         /* WHERE & HAVING clauses */
   ulong options;
   List<List_item>     expr_list;
-  List<List_item>     when_list;
-  SQL_LIST	      order_list,table_list,group_list;
-  List<Item>          item_list;
-  List<String>        interval_list,use_index, *use_index_ptr,
+  List<List_item>     when_list;                /* WHEN clause */
+  SQL_LIST	      table_list, group_list;   /* FROM & GROUP BY clauses */
+  List<Item>          item_list; /* list of fields & expressions */
+  List<String>        interval_list, use_index, *use_index_ptr,
 		      ignore_index, *ignore_index_ptr;
   List<Item_func_match> ftfunc_list;
   uint in_sum_expr, sort_default;
-  bool	create_refs, braces;
-  st_select_lex *next, *prev;
-} SELECT_LEX;
-
+  bool	create_refs, 
+    braces; /* SELECT ... UNION (SELECT ... ) <- this braces */
+  void init_query();
+  void init_select();
+};
+typedef struct st_select_lex SELECT_LEX;
 
 class Set_option :public Sql_alloc {
 public:
@@ -137,13 +252,15 @@ class Set_option :public Sql_alloc {
     :name(par_name), item(par_item), name_length(length), type(par_type) {}
 };
 
-
 /* The state of the lex parsing. This is saved in the THD struct */
 
 typedef struct st_lex {
   uint	 yylineno,yytoklen;			/* Simulate lex */
   LEX_YYSTYPE yylval;
-  SELECT_LEX select_lex, *select, *last_select;
+  SELECT_LEX_UNIT unit;                         /* most upper unit */
+  SELECT_LEX select_lex,                        /* first SELECT_LEX */
+    /* current SELECT_LEX in parsing */
+    *select;
   uchar *ptr,*tok_start,*tok_end,*end_of_query;
   char *length,*dec,*change,*name;
   char *backup_dir;				/* For RESTORE/BACKUP */

sql/sql_parse.cc

@@ -1203,11 +1203,12 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
 void
 mysql_execute_command(void)
 {
-  int	res=0;
-  THD	*thd=current_thd;
+  int	res= 0;
+  THD	*thd= current_thd;
   LEX	*lex= &thd->lex;
-  TABLE_LIST *tables=(TABLE_LIST*) lex->select_lex.table_list.first;
-  SELECT_LEX *select_lex = lex->select;
+  TABLE_LIST *tables= (TABLE_LIST*) lex->select_lex.table_list.first;
+  SELECT_LEX *select_lex= lex->select;
+  SELECT_LEX_UNIT *unit= &lex->unit;
   DBUG_ENTER("mysql_execute_command");
 
   if (thd->slave_thread)
@@ -1240,8 +1241,10 @@ mysql_execute_command(void)
   {
     for (TABLE_LIST *cursor= tables;
 	 cursor;
-	 cursor=cursor->next)
-      if (cursor->derived && mysql_derived(thd,lex,(SELECT_LEX *)cursor->derived,cursor))
+	 cursor= cursor->next)
+      if (cursor->derived && mysql_derived(thd, lex,
+					   (SELECT_LEX_UNIT *)cursor->derived,
+					   cursor))
 	DBUG_VOID_RETURN;
   }
   if ((lex->select_lex.next && create_total_list(thd,lex,&tables)) ||
@@ -1272,11 +1275,11 @@ mysql_execute_command(void)
       break;					// Error message is given
     }
 
-    thd->offset_limit=select_lex->offset_limit;
-    thd->select_limit=select_lex->select_limit+select_lex->offset_limit;
-    if (thd->select_limit < select_lex->select_limit)
-      thd->select_limit= HA_POS_ERROR;		// no limit
-    if (thd->select_limit == HA_POS_ERROR)
+    unit->offset_limit_cnt =select_lex->offset_limit;
+    unit->select_limit_cnt =select_lex->select_limit+select_lex->offset_limit;
+    if (unit->select_limit_cnt < select_lex->select_limit)
+      unit->select_limit_cnt= HA_POS_ERROR;		// no limit
+    if (unit->select_limit_cnt == HA_POS_ERROR)
       select_lex->options&= ~OPTION_FOUND_ROWS;
 
     if (lex->exchange)
@@ -1501,10 +1504,11 @@ mysql_execute_command(void)
 	for (table = tables->next ; table ; table=table->next)
 	  table->lock_type= lex->lock_option;
       }
-      thd->offset_limit=select_lex->offset_limit;
-      thd->select_limit=select_lex->select_limit+select_lex->offset_limit;
-      if (thd->select_limit < select_lex->select_limit)
-	thd->select_limit= HA_POS_ERROR;		// No limit
+      unit->offset_limit_cnt= select_lex->offset_limit;
+      unit->select_limit_cnt= select_lex->select_limit+
+	select_lex->offset_limit;
+      if (unit->select_limit_cnt < select_lex->select_limit)
+	unit->select_limit_cnt= HA_POS_ERROR;		// No limit
 
       /* Skip first table, which is the table we are creating */
       lex->select_lex.table_list.first=
@@ -1786,13 +1790,13 @@ mysql_execute_command(void)
 	while ((item=value_list++))
 	  total_list.push_back(item);
 	
-	res=mysql_select(thd,tables,total_list,
-			 select_lex->where,
-			 (ORDER *)NULL,(ORDER *)NULL,(Item *)NULL,
-			 (ORDER *)NULL,
-			 select_lex->options | thd->options |
-			 SELECT_NO_JOIN_CACHE,
-			 result);
+	res= mysql_select(thd, tables, total_list,
+			  select_lex->where,
+			  (ORDER *)NULL, (ORDER *)NULL, (Item *)NULL,
+			  (ORDER *)NULL,
+			  select_lex->options | thd->options |
+			  SELECT_NO_JOIN_CACHE,
+			  result, unit);
 	delete result;
       }
       else
@@ -1842,10 +1846,10 @@ mysql_execute_command(void)
     }
 
     select_result *result;
-    thd->offset_limit=select_lex->offset_limit;
-    thd->select_limit=select_lex->select_limit+select_lex->offset_limit;
-    if (thd->select_limit < select_lex->select_limit)
-      thd->select_limit= HA_POS_ERROR;		// No limit
+    unit->offset_limit_cnt= select_lex->offset_limit;
+    unit->select_limit_cnt= select_lex->select_limit+select_lex->offset_limit;
+    if (unit->select_limit_cnt < select_lex->select_limit)
+      unit->select_limit_cnt= HA_POS_ERROR;		// No limit
 
     if (check_dup(tables->db, tables->real_name, tables->next))
     {
@@ -1961,7 +1965,7 @@ mysql_execute_command(void)
 		       (ORDER *)NULL,
 		       select_lex->options | thd->options |
 		       SELECT_NO_JOIN_CACHE,
-		       result);
+		       result, unit);
       delete result;
     }
     else
@@ -2664,18 +2668,21 @@ static void
 mysql_init_query(THD *thd)
 {
   DBUG_ENTER("mysql_init_query");
-  thd->lex.select_lex.item_list.empty();
+  thd->lex.unit.init_query();
+  thd->lex.unit.init_select();
+  thd->lex.select_lex.init_query();
+  thd->lex.unit.slave= &thd->lex.select_lex;
+  thd->lex.unit.select_limit= thd->default_select_limit; //Global limit
+  thd->lex.select_lex.master= &thd->lex.unit;
+  thd->lex.select_lex.prev= &thd->lex.unit.slave;
   thd->lex.value_list.empty();
-  thd->lex.select_lex.table_list.elements=0;
-  thd->free_list=0;  thd->lex.union_option=0;
-  thd->lex.select = thd->lex.last_select = &thd->lex.select_lex;
-  thd->lex.select_lex.table_list.first=0;
-  thd->lex.select_lex.table_list.next= (byte**) &thd->lex.select_lex.table_list.first;
-  thd->lex.select_lex.next=0;
-  thd->fatal_error=0;				// Safety
-  thd->last_insert_id_used=thd->query_start_used=thd->insert_id_used=0;
-  thd->sent_row_count=thd->examined_row_count=0;
-  thd->safe_to_cache_query=1;
+  thd->free_list= 0;
+  thd->lex.union_option= 0;
+  thd->lex.select= &thd->lex.select_lex;
+  thd->fatal_error= 0;				// Safety
+  thd->last_insert_id_used= thd->query_start_used= thd->insert_id_used=0;
+  thd->sent_row_count= thd->examined_row_count= 0;
+  thd->safe_to_cache_query= 1;
   DBUG_VOID_RETURN;
 }
 
@@ -2683,53 +2690,53 @@ void
 mysql_init_select(LEX *lex)
 {
   SELECT_LEX *select_lex = lex->select;
-  select_lex->where=select_lex->having=0;
+  select_lex->init_select();
   select_lex->select_limit=lex->thd->default_select_limit;
   select_lex->offset_limit=0;
-  select_lex->options=0;
-  select_lex->linkage=UNSPECIFIED_TYPE;
   lex->exchange = 0;
   lex->proc_list.first=0;
-  select_lex->order_list.elements=select_lex->group_list.elements=0;
-  select_lex->order_list.first=0;
-  select_lex->order_list.next= (byte**) &select_lex->order_list.first;
-  select_lex->group_list.first=0;
-  select_lex->group_list.next= (byte**) &select_lex->group_list.first;
-  select_lex->next = select_lex->prev = (SELECT_LEX *)NULL; 
 }
 
 bool
-mysql_new_select(LEX *lex)
+mysql_new_select(LEX *lex, bool move_down)
 {
   SELECT_LEX *select_lex = (SELECT_LEX *) lex->thd->calloc(sizeof(SELECT_LEX));
   if (!select_lex)
     return 1;
-  lex->select=lex->last_select;
-  lex->select->next=select_lex; 
-  lex->select=lex->last_select=select_lex;
-  select_lex->table_list.next= (byte**) &select_lex->table_list.first;
-  select_lex->item_list.empty();
-  select_lex->when_list.empty(); 
-  select_lex->expr_list.empty();
-  select_lex->interval_list.empty(); 
-  select_lex->use_index.empty();
-  select_lex->ftfunc_list.empty();
+  select_lex->init_query();
+  select_lex->init_select();
+  if (move_down)
+  {
+    /* first select_lex of subselect or derived table */
+    SELECT_LEX_UNIT *unit= 
+      (SELECT_LEX_UNIT *) lex->thd->calloc(sizeof(SELECT_LEX_UNIT));
+    if (!unit)
+      return 1;
+    unit->init_query();
+    unit->init_select();
+    unit->include_down(lex->select);
+    select_lex->include_down(unit);
+  }
+  else
+    select_lex->include_neighbour(lex->select);
+    
+  ((SELECT_LEX_UNIT*)select_lex->master)->global_parameters= select_lex;
+  select_lex->include_global(&lex->select->link_next);
+  lex->select= select_lex;
   return 0;
 }
 
 void mysql_init_multi_delete(LEX *lex)
 {
-  lex->sql_command =  SQLCOM_DELETE_MULTI;
+  lex->sql_command=  SQLCOM_DELETE_MULTI;
   mysql_init_select(lex);
-  lex->select->select_limit=HA_POS_ERROR;
-  lex->auxilliary_table_list=lex->select_lex.table_list;
-  lex->select->table_list.elements=0; 
-  lex->select->table_list.first=0;
-  lex->select->table_list.next= (byte**) &(lex->select->table_list.first);
+  lex->select->select_limit= HA_POS_ERROR;
+  lex->auxilliary_table_list= lex->select_lex.table_list;
+  lex->select->init_query();
 }
 
 void
-mysql_parse(THD *thd,char *inBuf,uint length)
+mysql_parse(THD *thd, char *inBuf, uint length)
 {
   DBUG_ENTER("mysql_parse");
 
@@ -3159,7 +3166,7 @@ TABLE_LIST *add_table_to_list(Table_ident *table, LEX_STRING *alias,
   ptr->real_name_length=table->table.length;
   ptr->lock_type=flags;
   ptr->updating=updating;
-  ptr->derived=(SELECT_LEX *)table->sel;
+  ptr->derived= (SELECT_LEX_UNIT *) table->sel;
   if (use_index)
     ptr->use_index=(List<String> *) thd->memdup((gptr) use_index,
 					       sizeof(*use_index));
@@ -3204,8 +3211,8 @@ static bool create_total_list(THD *thd, LEX *lex, TABLE_LIST **result)
   SELECT_LEX *sl;
   TABLE_LIST **new_table_list= result, *aux;
 
-  *new_table_list=0;				// end result list
-  for (sl= &lex->select_lex; sl; sl=sl->next)
+  *new_table_list= 0;				// end result list
+  for (sl= &lex->select_lex; sl; sl= (SELECT_LEX *) sl->next)
   {
     if (sl->order_list.first && sl->next && !sl->braces)
     {

sql/sql_select.h

@@ -173,6 +173,8 @@ class JOIN {
   select_result *result;
   TMP_TABLE_PARAM tmp_table_param;
   MYSQL_LOCK *lock;
+  // unit structure (with global parameters) for this select
+  SELECT_LEX_UNIT *unit;
 };
 
 
@@ -187,7 +189,8 @@ void TEST_join(JOIN *join);
 bool store_val_in_field(Field *field,Item *val);
 TABLE *create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
 			ORDER *group, bool distinct, bool save_sum_fields,
-			bool allow_distinct_limit, ulong select_options);
+			bool allow_distinct_limit, ulong select_options,
+			SELECT_LEX_UNIT *unit);
 void free_tmp_table(THD *thd, TABLE *entry);
 void count_field_types(TMP_TABLE_PARAM *param, List<Item> &fields,
 		       bool reset_with_sum_func);

sql/sql_union.cc

@@ -27,8 +27,8 @@
 
 int mysql_union(THD *thd, LEX *lex,select_result *result)
 {
-  SELECT_LEX *sl, *last_sl, *lex_sl;
-  ORDER *order;
+  SELECT_LEX *sl;
+  SELECT_LEX_UNIT *unit= &(lex->unit);
   List<Item> item_list;
   TABLE *table;
   int describe=(lex->select_lex.options & SELECT_DESCRIBE) ? 1 : 0;
@@ -39,12 +39,12 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
   TMP_TABLE_PARAM tmp_table_param;
   select_union *union_result;
   DBUG_ENTER("mysql_union");
+  st_select_lex_node * global;
 
   /* Fix tables 'to-be-unioned-from' list to point at opened tables */
-  last_sl= &lex->select_lex;
-  for (sl= last_sl;
-       sl && sl->linkage != NOT_A_SELECT;
-       last_sl=sl, sl=sl->next)
+  for (sl= &lex->select_lex;
+       sl;
+       sl= (SELECT_LEX *) sl->next)
   {
     for (TABLE_LIST *cursor= (TABLE_LIST *)sl->table_list.first;
 	 cursor;
@@ -52,31 +52,13 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
       cursor->table= ((TABLE_LIST*) cursor->table)->table;
   }
 
-  /* last_sel now points at the last select where the ORDER BY is stored */
-  if (sl)
+  /* Global option */
+  if (((void*)(global= unit->global_parameters)) == ((void*)unit))
   {
-    /*
-      The found SL is an extra SELECT_LEX argument that contains
-      the ORDER BY and LIMIT parameter for the whole UNION
-    */
-    lex_sl= sl;
-    order=  (ORDER *) lex_sl->order_list.first;
-    found_rows_for_union = lex->select_lex.options & OPTION_FOUND_ROWS && !describe && sl->select_limit;
+    found_rows_for_union = lex->select_lex.options & OPTION_FOUND_ROWS && 
+      !describe && global->select_limit;
     if (found_rows_for_union)
       lex->select_lex.options ^=  OPTION_FOUND_ROWS;
-// This is done to eliminate unnecessary slowing down of the first query 
-    if (!order || !describe) 
-      last_sl->next=0;				// Remove this extra element
-  }
-  else if (!last_sl->braces)
-  {
-    lex_sl= last_sl;				// ORDER BY is here
-    order=  (ORDER *) lex_sl->order_list.first;
-  }
-  else
-  {
-    lex_sl=0;
-    order=0;
   }
   
   if (describe)
@@ -113,11 +95,12 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
 
   bzero((char*) &tmp_table_param,sizeof(tmp_table_param));
   tmp_table_param.field_count=item_list.elements;
-  if (!(table=create_tmp_table(thd, &tmp_table_param, item_list,
-			       (ORDER*) 0, !describe & !lex->union_option,
-			       1, 0,
-			       (lex->select_lex.options | thd->options |
-				TMP_TABLE_ALL_COLUMNS))))
+  if (!(table= create_tmp_table(thd, &tmp_table_param, item_list,
+				(ORDER*) 0, !describe & !lex->union_option,
+				1, 0,
+				(lex->select_lex.options | thd->options |
+				 TMP_TABLE_ALL_COLUMNS),
+				unit)))
     DBUG_RETURN(-1);
   table->file->extra(HA_EXTRA_WRITE_CACHE);
   table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
@@ -133,25 +116,29 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
   }
   union_result->save_time_stamp=!describe;
 
-  for (sl= &lex->select_lex; sl; sl=sl->next)
+  for (sl= &lex->select_lex; sl; sl= (SELECT_LEX*) sl->next)
   {
     lex->select=sl;
-    thd->offset_limit=sl->offset_limit;
-    thd->select_limit=sl->select_limit+sl->offset_limit;
-    if (thd->select_limit < sl->select_limit)
-      thd->select_limit= HA_POS_ERROR;		// no limit
-    if (thd->select_limit == HA_POS_ERROR)
+    unit->offset_limit_cnt= sl->offset_limit;
+    unit->select_limit_cnt= sl->select_limit+sl->offset_limit;
+    if (unit->select_limit_cnt < sl->select_limit)
+      unit->select_limit_cnt= HA_POS_ERROR;		// no limit
+    if (unit->select_limit_cnt == HA_POS_ERROR)
       sl->options&= ~OPTION_FOUND_ROWS;
 
-    res=mysql_select(thd, (describe && sl->linkage==NOT_A_SELECT) ? first_table :  (TABLE_LIST*) sl->table_list.first,
-		     sl->item_list,
-		     sl->where,
-		     (sl->braces) ? (ORDER *)sl->order_list.first : (ORDER *) 0,
-		     (ORDER*) sl->group_list.first,
-		     sl->having,
-		     (ORDER*) NULL,
-		     sl->options | thd->options | SELECT_NO_UNLOCK | ((describe) ? SELECT_DESCRIBE : 0),
-		     union_result);
+    res= mysql_select(thd, 
+		      (describe && sl->linkage==GLOBAL_OPTIONS_TYPE) ? 
+		      first_table :  (TABLE_LIST*) sl->table_list.first,
+		      sl->item_list,
+		      sl->where,
+		      (sl->braces) ? 
+		      (ORDER *)sl->order_list.first : (ORDER *) 0,
+		      (ORDER*) sl->group_list.first,
+		      sl->having,
+		      (ORDER*) NULL,
+		      sl->options | thd->options | 
+		      SELECT_NO_UNLOCK | ((describe) ? SELECT_DESCRIBE : 0),
+		      union_result, unit);
     if (res)
       goto exit;
   }
@@ -183,26 +170,20 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
     }
     if (!thd->fatal_error)			// Check if EOM
     {
-      if (lex_sl)
-      {
-	thd->offset_limit=lex_sl->offset_limit;
-	thd->select_limit=lex_sl->select_limit+lex_sl->offset_limit;
-	if (thd->select_limit < lex_sl->select_limit)
-	  thd->select_limit= HA_POS_ERROR;		// no limit
-	if (thd->select_limit == HA_POS_ERROR)
-	  thd->options&= ~OPTION_FOUND_ROWS;
-      }
-      else 
-      {
-	thd->offset_limit= 0;
-	thd->select_limit= thd->default_select_limit;
-      }
+      st_select_lex_node * global= unit->global_parameters;
+      unit->offset_limit_cnt= global->offset_limit;
+      unit->select_limit_cnt= global->select_limit+global->offset_limit;
+      if (unit->select_limit_cnt < global->select_limit)
+	unit->select_limit_cnt= HA_POS_ERROR;		// no limit
+      if (unit->select_limit_cnt == HA_POS_ERROR)
+	thd->options&= ~OPTION_FOUND_ROWS;
       if (describe)
-	thd->select_limit= HA_POS_ERROR;		// no limit
-      res=mysql_select(thd,&result_table_list,
-		       item_list, NULL, (describe) ? 0 : order,
-		       (ORDER*) NULL, NULL, (ORDER*) NULL,
-		       thd->options, result);
+	unit->select_limit_cnt= HA_POS_ERROR;		// no limit
+      res= mysql_select(thd,&result_table_list,
+			item_list, NULL,
+			(describe) ? 0 : (ORDER*)global->order_list.first,
+			(ORDER*) NULL, NULL, (ORDER*) NULL,
+			thd->options, result, unit);
       if (found_rows_for_union && !res)
 	thd->limit_found_rows = (ulonglong)table->file->records;
     }
@@ -226,7 +207,7 @@ select_union::select_union(TABLE *table_par)
     We can always use DUP_IGNORE because the temporary table will only
     contain a unique key if we are using not using UNION ALL
   */
-  info.handle_duplicates=DUP_IGNORE;
+  info.handle_duplicates= DUP_IGNORE;
 }
 
 select_union::~select_union()
@@ -234,8 +215,9 @@ select_union::~select_union()
 }
 
 
-int select_union::prepare(List<Item> &list)
+int select_union::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
 {
+  unit= u;
   if (save_time_stamp && list.elements != table->fields)
   {
     my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
@@ -247,9 +229,9 @@ int select_union::prepare(List<Item> &list)
 
 bool select_union::send_data(List<Item> &values)
 {
-  if (thd->offset_limit)
+  if (unit->offset_limit_cnt)
   {						// using limit offset,count
-    thd->offset_limit--;
+    unit->offset_limit_cnt--;
     return 0;
   }
   fill_record(table->field,values);

sql/sql_update.cc

@@ -379,9 +379,10 @@ multi_update::multi_update(THD *thd_arg, TABLE_LIST *ut, List<Item> &fs,
 }
 
 int
-multi_update::prepare(List<Item> &values)
+multi_update::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
 {
   DBUG_ENTER("multi_update::prepare");
+  unit= u;
   do_update = true;   
   thd->count_cuted_fields=1;
   thd->cuted_fields=0L;
@@ -466,15 +467,19 @@ multi_update::prepare(List<Item> &values)
       }
       if (counter)
       {
-	Field_string offset(table_ref->table->file->ref_length,false,"offset",table_ref->table,true);
+	Field_string offset(table_ref->table->file->ref_length, false,
+			    "offset", table_ref->table, true);
 	temp_fields->push_front(new Item_field(((Field *)&offset)));
 // Here I make tmp tables
 	int cnt=counter-1;
 	TMP_TABLE_PARAM tmp_table_param;
 	bzero((char*) &tmp_table_param,sizeof(tmp_table_param));
 	tmp_table_param.field_count=temp_fields->elements;
-	if (!(tmp_tables[cnt]=create_tmp_table(thd, &tmp_table_param, *temp_fields,
-						   (ORDER*) 0, 1, 0, 0, TMP_TABLE_ALL_COLUMNS)))
+	if (!(tmp_tables[cnt]=create_tmp_table(thd, &tmp_table_param,
+					       *temp_fields,
+					       (ORDER*) 0, 1, 0, 0,
+					       TMP_TABLE_ALL_COLUMNS,
+					       unit)))
 	{
 	  error = 1; // A proper error message is due here 
 	  DBUG_RETURN(1);

sql/sql_yacc.yy

@@ -1449,7 +1449,14 @@ select:
 select_init:
 	SELECT_SYM select_part2 { Select->braces=false;	} union
 	|
-	'(' SELECT_SYM 	select_part2 ')' { Select->braces=true;} union_opt
+	'(' SELECT_SYM 	select_part2 ')' 
+	  { 
+            SELECT_LEX * sel=Select;
+	    sel->braces=true;
+            /* select in braces, can't contain global parameters */
+            ((SELECT_LEX_UNIT*)sel->master)->global_parameters=
+              sel->master;
+          } union_opt
 
 
 select_part2:
@@ -2155,23 +2162,22 @@ join_table:
         | '(' SELECT_SYM select_part3 ')' opt_table_alias 
 	{
 	  LEX *lex=Lex;
-	  SELECT_LEX *select_to_execute= lex->select;
-	  lex->select=lex->select->prev;
-	  if (!($$=add_table_to_list(new Table_ident(select_to_execute),
-	                             $5,0,TL_UNLOCK)))
+	  SELECT_LEX_UNIT *unit= (SELECT_LEX_UNIT*) lex->select->master;
+	  lex->select= (SELECT_LEX*) unit->master;
+	  if (!($$= add_table_to_list(new Table_ident(unit),
+	                              $5,0,TL_UNLOCK)))
 	    YYABORT;
 	}
 
 select_part3:
         {
-	  LEX *lex=Lex;
-	  lex->derived_tables=true;
-	  SELECT_LEX *tmp=lex->select;
-	  if (lex->select->linkage == NOT_A_SELECT || mysql_new_select(lex))
+	  LEX *lex= Lex;
+	  lex->derived_tables= true;
+	  if (lex->select->linkage == GLOBAL_OPTIONS_TYPE || 
+              mysql_new_select(lex, 1))
 	    YYABORT;
 	  mysql_init_select(lex);
-	  lex->select->linkage=DERIVED_TABLE_TYPE;
-	  lex->select->prev=tmp;
+	  lex->select->linkage= DERIVED_TABLE_TYPE;
 	}
         select_options select_item_list select_intoto
 
@@ -3811,7 +3817,8 @@ union_list:
        net_printf(&lex->thd->net, ER_WRONG_USAGE,"UNION","INTO");
        YYABORT;
     } 
-    if (lex->select->linkage == NOT_A_SELECT || mysql_new_select(lex))
+    if (lex->select->linkage == GLOBAL_OPTIONS_TYPE || 
+	mysql_new_select(lex, 0))
       YYABORT;
     lex->select->linkage=UNION_TYPE;
   } 
@@ -3826,10 +3833,15 @@ optional_order_or_limit:
   |
   {
     LEX *lex=Lex;
-    if (!lex->select->braces || mysql_new_select(lex))
+    if (!lex->select->braces)
      YYABORT;
-    mysql_init_select(lex);
-    lex->select->linkage=NOT_A_SELECT;
+    ((SELECT_LEX_UNIT*)lex->select->master)->global_parameters= 
+      lex->select->master;
+    /*
+      Following type conversion looks like hack, but all that need SELECT_LEX 
+      fields always check linkage type.
+    */
+    lex->select= (SELECT_LEX*)lex->select->master;
     lex->select->select_limit=lex->thd->default_select_limit;
   }
   opt_order_clause limit_clause

sql/table.h

@@ -139,18 +139,18 @@ typedef struct st_table_list {
   struct	st_table_list *next;
   char		*db,*name,*real_name;
   uint32        db_length, real_name_length;
-  Item		*on_expr;			/* Used with outer join */
-  struct st_table_list *natural_join;		/* natural join on this table*/
+  Item		*on_expr;		 /* Used with outer join */
+  struct st_table_list *natural_join;	 /* natural join on this table*/
   /* ... join ... USE INDEX ... IGNORE INDEX */
-  List<String>	*use_index,*ignore_index; 
+  List<String>	*use_index, *ignore_index; 
   TABLE		*table;
   GRANT_INFO	grant;
   thr_lock_type lock_type;
-  uint		outer_join;			/* Which join type */
-  bool		straight;			/* optimize with prev table */
-  bool          updating;                   /* for replicate-do/ignore table */
-  bool		shared;				/* Used twice in union */
-  void    *derived;
+  uint		outer_join;		 /* Which join type */
+  bool		straight;		 /* optimize with prev table */
+  bool          updating;                /* for replicate-do/ignore table */
+  bool		shared;			 /* Used twice in union */
+  void          *derived;                /* SELECT_LEX_UNIT of derived table */
 } TABLE_LIST;
 
 typedef struct st_changed_table_list {