(SCRUM)

It looks like samll revolution in SELECT_LEX tree, but it was only natural way to solve problem with name resolution of external fields inside subselect which belongs to global order of union
also it have following advantages:
 - removed mess with current_select type conversion
   - type checking/converting
   - a lot of virtual methods
 - fake select for union execution allocated only once (it was allocated for every subselect with union executing)

changes:
fixed bug with outer fields name resolution of subqueries which belong to global ORDER BY clause
remuved select_lex() function, now thd->lex.current_select always have type SELECT_LEX
new SELECT_LEX (fake_select_lex) will be allocated in case of UNION for using in UNION processing
fake_select_lex allocated for union hold global ORDER BY & LIMIT clauses and have linkage equal to GLOBAL_OPTIONS_TYPE 
new description of SELECT_LEX tree

(SCRUM)

1 files changed, 62 insertions, 80 deletions

diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 9b372f6eeda..8e3d6df0540 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -966,27 +966,17 @@ void st_select_lex_node::init_query()
   options= 0;
   linkage= UNSPECIFIED_TYPE;
   no_table_names_allowed= uncacheable= dependent= 0;
-  ref_pointer_array= 0;
-  cond_count= 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;
-  select_items= 0;
-  with_sum_func= 0;
-  parsing_place= SELECT_LEX_NODE::NO_MATTER;
 }
 
 void st_select_lex_unit::init_query()
 {
   st_select_lex_node::init_query();
   linkage= GLOBAL_OPTIONS_TYPE;
-  global_parameters= this;
+  global_parameters= first_select();
   select_limit_cnt= HA_POS_ERROR;
   offset_limit_cnt= 0;
   union_option= 0;
@@ -994,6 +984,7 @@ void st_select_lex_unit::init_query()
   item= 0;
   union_result= 0;
   table= 0;
+  fake_select_lex= 0;
 }
 
 void st_select_lex::init_query()
@@ -1005,7 +996,8 @@ void st_select_lex::init_query()
   where= 0;
   olap= UNSPECIFIED_OLAP_TYPE;
   insert_select= having_fix_field= 0;
-  with_wild= 0;
+  cond_count= with_wild= 0;
+  ref_pointer_array= 0;
 }
 
 void st_select_lex::init_select()
@@ -1027,6 +1019,14 @@ void st_select_lex::init_select()
   ftfunc_list_alloc.empty();
   ftfunc_list= &ftfunc_list_alloc;
   linkage= UNSPECIFIED_TYPE;
+  order_list.elements= 0;
+  order_list.first= 0;
+  order_list.next= (byte**) &order_list.first;
+  select_limit= HA_POS_ERROR;
+  offset_limit= 0;
+  select_items= 0;
+  with_sum_func= 0;
+  parsing_place= SELECT_LEX_NODE::NO_MATTER;
 }
 
 /*
@@ -1044,6 +1044,23 @@ void st_select_lex_node::include_down(st_select_lex_node *upper)
   slave= 0;
 }
 
+/*
+  include on level down (but do not link)
+  
+  SYNOPSYS
+    st_select_lex_node::include_standalone()
+    upper - reference on node underr which this node should be included
+    ref - references on reference on this node
+*/
+void st_select_lex_node::include_standalone(st_select_lex_node *upper,
+					    st_select_lex_node **ref)
+{
+  next= 0;
+  prev= ref;
+  master= upper;
+  slave= 0;
+}
+
 /* include neighbour (on same level) */
 void st_select_lex_node::include_neighbour(st_select_lex_node *before)
 {
@@ -1125,33 +1142,6 @@ void st_select_lex_unit::exclude_level()
     (*prev)= next;
 }
 
-st_select_lex* st_select_lex_node::select_lex()
-{
-  DBUG_ENTER("st_select_lex_node::select_lex (never should be called)");
-  DBUG_ASSERT(0);
-  DBUG_RETURN(0);
-}
-
-bool st_select_lex_node::add_item_to_list(THD *thd, Item *item)
-{
-  return 1;
-}
-
-bool st_select_lex_node::add_group_to_list(THD *thd, Item *item, bool asc)
-{
-  return 1;
-}
-
-bool st_select_lex_node::add_order_to_list(THD *thd, Item *item, bool asc)
-{
-  return add_to_list(thd, order_list, item, asc);
-}
-
-bool st_select_lex_node::add_ftfunc_to_list(Item_func_match *func)
-{
-  return 1;
-}
-
 /*
   st_select_lex_node::mark_as_dependent mark all st_select_lex struct from 
   this to 'last' as dependent
@@ -1165,31 +1155,26 @@ bool st_select_lex_node::add_ftfunc_to_list(Item_func_match *func)
 
 */
 
-void st_select_lex_node::mark_as_dependent(SELECT_LEX *last)
+void st_select_lex::mark_as_dependent(SELECT_LEX *last)
 {
   /*
     Mark all selects from resolved to 1 before select where was
     found table as depended (of select where was found table)
   */
-  for (SELECT_LEX_NODE *s= this;
+  for (SELECT_LEX *s= this;
        s &&s != last;
        s= s->outer_select())
     if ( !s->dependent )
     {
       // Select is dependent of outer select
       s->dependent= 1;
-      if (s->linkage != GLOBAL_OPTIONS_TYPE)
-      { 
-	//s is st_select_lex*
-
-	s->master_unit()->dependent= 1;
-	//Tables will be reopened many times
-	for (TABLE_LIST *tbl=
-	       s->get_table_list();
-	     tbl;
-	     tbl= tbl->next)
-	  tbl->shared= 1;
-      }
+      s->master_unit()->dependent= 1;
+      //Tables will be reopened many times
+      for (TABLE_LIST *tbl=
+	     s->get_table_list();
+	   tbl;
+	   tbl= tbl->next)
+	tbl->shared= 1;
     }
 }
 
@@ -1200,15 +1185,6 @@ TABLE_LIST* st_select_lex_node::get_table_list()     { return 0; }
 List<Item>* st_select_lex_node::get_item_list()      { return 0; }
 List<String>* st_select_lex_node::get_use_index()    { return 0; }
 List<String>* st_select_lex_node::get_ignore_index() { return 0; }
-TABLE_LIST *st_select_lex_node::add_table_to_list(THD *thd, Table_ident *table,
-						  LEX_STRING *alias,
-						  ulong table_join_options,
-						  thr_lock_type flags,
-						  List<String> *use_index,
-						  List<String> *ignore_index)
-{
-  return 0;
-}
 
 ulong st_select_lex_node::get_table_join_options()
 {
@@ -1218,7 +1194,7 @@ ulong st_select_lex_node::get_table_join_options()
 /*
   prohibit using LIMIT clause
 */
-bool st_select_lex_node::test_limit()
+bool st_select_lex::test_limit()
 {
   if (select_limit != HA_POS_ERROR)
   {
@@ -1293,22 +1269,39 @@ bool st_select_lex_unit::create_total_list_n_last_return(THD *thd, st_lex *lex,
   TABLE_LIST *slave_list_first=0, **slave_list_last= &slave_list_first;
   TABLE_LIST **new_table_list= *result, *aux;
   SELECT_LEX *sl= (SELECT_LEX*)slave;
-  for (; sl; sl= sl->next_select())
+  
+  /*
+    iterate all inner selects + fake_select (if exists),
+    fake_select->next_select() always is 0
+  */
+  for (;
+       sl;
+       sl= (sl->next_select() ?
+	    sl->next_select() :
+	    (sl == fake_select_lex ?
+	     0 :
+	     fake_select_lex)))
   {
     // check usage of ORDER BY in union
-    if (sl->order_list.first && sl->next_select() && !sl->braces)
+    if (sl->order_list.first && sl->next_select() && !sl->braces &&
+	sl->linkage != GLOBAL_OPTIONS_TYPE)
     {
       net_printf(thd,ER_WRONG_USAGE,"UNION","ORDER BY");
       return 1;
     }
+
     if (sl->linkage == DERIVED_TABLE_TYPE && !check_derived)
-      continue;
+      goto end;
+
     for (SELECT_LEX_UNIT *inner=  sl->first_inner_unit();
 	 inner;
 	 inner= inner->next_unit())
+    {
       if (inner->create_total_list_n_last_return(thd, lex,
 						 &slave_list_last, 0))
 	return 1;
+    }
+
     if ((aux= (TABLE_LIST*) sl->table_list.first))
     {
       TABLE_LIST *next;
@@ -1342,6 +1335,7 @@ bool st_select_lex_unit::create_total_list_n_last_return(THD *thd, st_lex *lex,
       }
     }
   }
+end:
   if (slave_list_first)
   {
     *new_table_list= slave_list_first;
@@ -1361,9 +1355,9 @@ st_select_lex* st_select_lex_unit::outer_select()
   return (st_select_lex*) master;
 }
 
-st_select_lex* st_select_lex::select_lex()
+bool st_select_lex::add_order_to_list(THD *thd, Item *item, bool asc)
 {
-  return this;
+  return add_to_list(thd, order_list, item, asc);
 }
 
 bool st_select_lex::add_item_to_list(THD *thd, Item *item)
@@ -1433,18 +1427,6 @@ ulong st_select_lex::get_table_join_options()
   return table_join_options;
 }
 
-st_select_lex::st_select_lex(struct st_lex *lex)
-  :fake_select(0)
-{
-  select_number= ++lex->thd->select_number;
-  init_query();
-  init_select();
-  include_neighbour(lex->current_select);
-  include_global((st_select_lex_node**)&lex->all_selects_list);
-  lex->current_select= this;
-}
-
-
 /*
   There are st_select_lex::add_table_to_list & 
   st_select_lex::set_lock_for_tables in sql_parse.cc