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fixed ALL/ANY optimisation with union (BUG#1668)

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code cleanup


mysql-test/r/subselect.result:
  test for BUG#1668
mysql-test/t/subselect.test:
  test for BUG#1668
sql/item_subselect.cc:
  removed unused class field
  fixed min_max subquery used_tables()/const()
  fixed ALL/ANY optimisation for unions
sql/item_subselect.h:
  removed unused class field
  fixed min_max subquery used_tables()/const()
sql/sql_union.cc:
  fixed result object assignment
This commit is contained in:
unknown 2003-10-27 01:01:27 +02:00
parent e559f1832c
commit 30764334f7
5 changed files with 56 additions and 10 deletions
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14
mysql-test/r/subselect.result
View file

@ -1489,3 +1489,17 @@ set sort_buffer_size = (select s1 from t1);
ERROR 21000: Subquery returns more than 1 row
do (select * from t1);
drop table t1;
create table t1 (s1 char);
insert into t1 values ('e');
select * from t1 where 'f' > any (select s1 from t1);
s1
e
select * from t1 where 'f' > any (select s1 from t1 union select s1 from t1);
s1
e
explain select * from t1 where 'f' > any (select s1 from t1 union select s1 from t1);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 system NULL NULL NULL NULL 1
2 SUBQUERY t1 system NULL NULL NULL NULL 1
3 UNION t1 system NULL NULL NULL NULL 1
drop table t1;

10
mysql-test/t/subselect.test
View file

@ -1010,3 +1010,13 @@ insert into t1 values (2);
set sort_buffer_size = (select s1 from t1);
do (select * from t1);
drop table t1;
#
# optimized ALL/ANY with union
#
create table t1 (s1 char);
insert into t1 values ('e');
select * from t1 where 'f' > any (select s1 from t1);
select * from t1 where 'f' > any (select s1 from t1 union select s1 from t1);
explain select * from t1 where 'f' > any (select s1 from t1 union select s1 from t1);
drop table t1;

27
sql/item_subselect.cc
View file

@ -35,7 +35,7 @@ inline Item * and_items(Item* cond, Item *item)
}
Item_subselect::Item_subselect():
Item_result_field(), engine_owner(1), value_assigned(0), substitution(0),
Item_result_field(), value_assigned(0), substitution(0),
engine(0), used_tables_cache(0), have_to_be_excluded(0),
const_item_cache(1), engine_changed(0)
{
@ -66,8 +66,7 @@ void Item_subselect::init(st_select_lex *select_lex,
Item_subselect::~Item_subselect()
{
if (engine_owner)
delete engine;
delete engine;
}
Item_subselect::trans_res
@ -183,7 +182,8 @@ Item_singlerow_subselect::Item_singlerow_subselect(st_select_lex *select_lex)
DBUG_VOID_RETURN;
}
Item_maxmin_subselect::Item_maxmin_subselect(st_select_lex *select_lex,
Item_maxmin_subselect::Item_maxmin_subselect(Item_subselect *parent,
st_select_lex *select_lex,
bool max)
:Item_singlerow_subselect()
{
@ -192,6 +192,14 @@ Item_maxmin_subselect::Item_maxmin_subselect(st_select_lex *select_lex,
max_columns= 1;
maybe_null= 1;
max_columns= 1;
/*
Following information was collected during performing fix_fields()
of Items belonged to subquery, which will be not repeated
*/
used_tables_cache= parent->get_used_tables_cache();
const_item_cache= parent->get_const_item_cache();
DBUG_VOID_RETURN;
}
@ -527,9 +535,16 @@ Item_in_subselect::single_value_transformer(JOIN *join,
func == &Item_bool_func2::ge_creator ||
func == &Item_bool_func2::le_creator))
{
if (substitution)
{
// It is second (third, ...) SELECT of UNION => All is done
DBUG_RETURN(RES_OK);
}
Item *subs;
if (!select_lex->group_list.elements &&
!select_lex->with_sum_func)
!select_lex->with_sum_func &&
!(select_lex->next_select()))
{
Item *item;
subs_type type= substype();
@ -565,7 +580,7 @@ Item_in_subselect::single_value_transformer(JOIN *join,
// remove LIMIT placed by ALL/ANY subquery
select_lex->master_unit()->global_parameters->select_limit=
HA_POS_ERROR;
subs= new Item_maxmin_subselect(select_lex,
subs= new Item_maxmin_subselect(this, select_lex,
(func == &Item_bool_func2::le_creator ||
func == &Item_bool_func2::lt_creator));
}

8
sql/item_subselect.h
View file

@ -33,7 +33,6 @@ typedef Item_bool_func2* (*compare_func_creator)(Item*, Item*);
class Item_subselect :public Item_result_field
{
my_bool engine_owner; /* Is this item owner of engine */
my_bool value_assigned; /* value already assigned to subselect */
protected:
/* thread handler, will be assigned in fix_fields only */
@ -90,6 +89,8 @@ public:
virtual void fix_length_and_dec();
table_map used_tables() const;
bool const_item() const;
inline table_map get_used_tables_cache() { return used_tables_cache; }
inline bool get_const_item_cache() { return const_item_cache; }
void update_used_tables();
void print(String *str)
{
@ -144,10 +145,11 @@ public:
};
/* used in static ALL/ANY optimisation */
class Item_maxmin_subselect: public Item_singlerow_subselect
class Item_maxmin_subselect :public Item_singlerow_subselect
{
public:
Item_maxmin_subselect(st_select_lex *select_lex, bool max);
Item_maxmin_subselect(Item_subselect *parent,
st_select_lex *select_lex, bool max);
};
/* exists subselect */

7
sql/sql_union.cc
View file

@ -119,13 +119,18 @@ int st_select_lex_unit::prepare(THD *thd, select_result *sel_result,
SELECT_LEX *select_cursor,*sl;
DBUG_ENTER("st_select_lex_unit::prepare");
/*
result object should be reassigned even if preparing already done for
max/min subquery (ALL/ANY optimization)
*/
result= sel_result;
if (prepared)
DBUG_RETURN(0);
prepared= 1;
res= 0;
found_rows_for_union= first_select_in_union()->options & OPTION_FOUND_ROWS;
TMP_TABLE_PARAM tmp_table_param;
result= sel_result;
t_and_f= tables_and_fields_initied;
bzero((char *)&tmp_table_param,sizeof(TMP_TABLE_PARAM));