derived tables with UNION's ...

Scrum task !!!!!

mysql-test/r/derived.result

@@ -63,6 +63,31 @@ a
 select 1 from (select 1) as a;
 1
 1
+select * from (select * from t1 union select * from t1) a;
+a	b
+1	a
+2	b
+3	c
+select * from (select * from t1 union all select * from t1) a;
+a	b
+1	a
+2	b
+3	c
+3	c
+1	a
+2	b
+3	c
+3	c
+explain select * from (select * from t1 union select * from t1) a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	3	
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	
+3	UNION	t1	ALL	NULL	NULL	NULL	NULL	4	
+explain select * from (select * from t1 union all select * from t1) a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	8	
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	
+3	UNION	t1	ALL	NULL	NULL	NULL	NULL	4	
 drop table if exists t1;
 create table t1(a int not null, t char(8), index(a));
 SELECT * FROM (SELECT * FROM t1) as b ORDER BY a  ASC LIMIT 0,20;

mysql-test/t/derived.test

@@ -24,6 +24,10 @@ drop table if exists  t1.t2,t3;
 select * from (select 1) as a;
 select a from (select 1 as a) as b;
 select 1 from (select 1) as a;
+select * from (select * from t1 union select * from t1) a;
+select * from (select * from t1 union all select * from t1) a;
+explain select * from (select * from t1 union select * from t1) a;
+explain select * from (select * from t1 union all select * from t1) a;
 drop table if exists t1;
 create table t1(a int not null, t char(8), index(a));
 disable_query_log;

sql/mysql_priv.h

@@ -419,7 +419,7 @@ int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit,
 			select_result *result);
 int mysql_explain_select(THD *thd, SELECT_LEX *sl, char const *type,
 			 select_result *result);
-int mysql_union(THD *thd, LEX *lex,select_result *result);
+int mysql_union(THD *thd, LEX *lex,select_result *result,SELECT_LEX_UNIT *unit);
 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,

sql/sql_analyse.cc

@@ -324,7 +324,7 @@ void field_str::add()
       }
       else
       {
-//	bzero((char*) &s, sizeof(s));  // Let tree handle free of this
+	bzero((char*) &s, sizeof(s));  // Let tree handle free of this
 	if ((treemem += length) > pc->max_treemem)
 	{
 	  room_in_tree = 0;	 // Remove tree, too big tree

sql/sql_derived.cc

@@ -41,8 +41,13 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
   select_union *derived_result;
   TABLE_LIST *tables= (TABLE_LIST *)sl->table_list.first;
   TMP_TABLE_PARAM tmp_table_param;
+  bool is_union=sl->next_select() && sl->next_select()->linkage == UNION_TYPE;
   DBUG_ENTER("mysql_derived");
   
+
+  if (is_union && unit->create_total_list(thd, lex, &tables))
+    DBUG_RETURN(-1);
+
   if (tables)
     res= check_table_access(thd,SELECT_ACL, tables);
   else
@@ -58,6 +63,19 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
     
   if (!(res=open_and_lock_tables(thd,tables)))
   {
+    if (is_union)
+    {
+      for (SELECT_LEX *sel= sl;
+	   sel;
+	   sel= sel->next_select())
+      {
+	for (TABLE_LIST *cursor= (TABLE_LIST *)sel->table_list.first;
+	     cursor;
+	     cursor=cursor->next)
+	  cursor->table= cursor->table_list->table;
+      }
+    }
+
     if (setup_fields(thd,tables,item_list,0,0,1))
     {
       res=-1;
@@ -66,7 +84,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, 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, item_list,
-			         (ORDER*) 0, 0, 1,
+			         (ORDER*) 0, is_union && !unit->union_option, 1,
 			         (sl->options | thd->options |
 				  TMP_TABLE_ALL_COLUMNS),
                                  HA_POS_ERROR)))
@@ -87,11 +105,14 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
 
       SELECT_LEX_NODE *save_current_select= lex->current_select;
       lex->current_select= sl;
-      res= mysql_select(thd, tables,  sl->item_list,
+      if (is_union)
+	res=mysql_union(thd,lex,derived_result,unit);
+      else
+	res= mysql_select(thd, tables,  sl->item_list,
 			sl->where, (ORDER *) sl->order_list.first,
 			(ORDER*) sl->group_list.first,
 			sl->having, (ORDER*) NULL,
-			sl->options | thd->options | SELECT_NO_UNLOCK,
+			sl->options | thd->options  | SELECT_NO_UNLOCK,
 			derived_result, unit, sl, 0);
       lex->current_select= save_current_select;
 
@@ -112,7 +133,12 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
 	      tables->table_list->table=tables->table; // to fix a problem in EXPLAIN
 	  }
 	  else
-	    sl->exclude();
+	  {
+	    if (is_union)
+	      unit->exclude();
+	    else
+	      sl->exclude();
+	  }
 	  t->db=(char *)"";
 	  t->derived=(SELECT_LEX *)0; // just in case ...
 	  table->file->info(HA_STATUS_VARIABLE);

sql/sql_lex.cc

@@ -995,7 +995,8 @@ void st_select_lex::init_select()
   use_index.empty();
   ftfunc_list_alloc.empty();
   ftfunc_list= &ftfunc_list_alloc;
-  linkage= UNSPECIFIED_TYPE;
+  if (linkage != UNION_TYPE)
+    linkage= UNSPECIFIED_TYPE;
 }
 
 /*
@@ -1206,7 +1207,7 @@ bool st_select_lex_unit::create_total_list_n_last_return(THD *thd, st_lex *lex,
       net_printf(thd,ER_WRONG_USAGE,"UNION","ORDER BY");
       return 1;
     }
-    if (sl->linkage == DERIVED_TABLE_TYPE)
+    if (sl->linkage == DERIVED_TABLE_TYPE && !sl->next_select())
       continue;
     for (SELECT_LEX_UNIT *inner=  sl->first_inner_unit();
 	 inner;

sql/sql_select.cc

@@ -162,7 +162,7 @@ int handle_select(THD *thd, LEX *lex, select_result *result)
   register SELECT_LEX *select_lex = &lex->select_lex;
   fix_tables_pointers(lex->all_selects_list);
   if (select_lex->next_select())
-    res=mysql_union(thd,lex,result);
+    res=mysql_union(thd,lex,result,&lex->unit);
   else
     res=mysql_select(thd,(TABLE_LIST*) select_lex->table_list.first,
 		     select_lex->item_list,

sql/sql_union.cc

@@ -24,10 +24,9 @@
 #include "mysql_priv.h"
 #include "sql_select.h"
 
-int mysql_union(THD *thd, LEX *lex, select_result *result)
+int mysql_union(THD *thd, LEX *lex, select_result *result,SELECT_LEX_UNIT *unit)
 {
   DBUG_ENTER("mysql_union");
-  SELECT_LEX_UNIT *unit= &lex->unit;
   int res= 0;
   if (!(res= unit->prepare(thd, result)))
     res= unit->exec();
@@ -125,8 +124,7 @@ int st_select_lex_unit::prepare(THD *thd, select_result *result)
   SELECT_LEX_NODE *lex_select_save= thd->lex.current_select;
   SELECT_LEX *sl;
 
-  if (lex_select_save->linkage != DERIVED_TABLE_TYPE)
-    thd->lex.current_select=first_select();
+  thd->lex.current_select=first_select();
   /* Global option */
   if (((void*)(global_parameters)) == ((void*)this))
   {