mirror of
https://github.com/MariaDB/server.git
synced 2025-01-20 22:12:30 +01:00
54a713aac5
Evaluate "NULL IN (SELECT ...)" in a special way: Disable pushed-down conditions and their "consequences": = Do full table scans instead of unique_[index_subquery] lookups. = Change appropriate "ref_or_null" accesses to full table scans in subquery's joins. Also cache value of NULL IN (SELECT ...) if the SELECT is not correlated wrt any upper select.
153 lines
6.2 KiB
Text
153 lines
6.2 KiB
Text
drop table if exists t0, t1, t2, t3, t4;
|
|
create table t1 (oref int, grp int, ie int) ;
|
|
insert into t1 (oref, grp, ie) values
|
|
(1, 1, 1),
|
|
(1, 1, 1),
|
|
(1, 2, NULL),
|
|
(2, 1, 3),
|
|
(3, 1, 4),
|
|
(3, 2, NULL);
|
|
create table t2 (oref int, a int);
|
|
insert into t2 values
|
|
(1, 1),
|
|
(2, 2),
|
|
(3, 3),
|
|
(4, NULL),
|
|
(2, NULL);
|
|
select a, oref, a in (select max(ie)
|
|
from t1 where oref=t2.oref group by grp) from t2;
|
|
a oref a in (select max(ie)
|
|
from t1 where oref=t2.oref group by grp)
|
|
1 1 1
|
|
2 2 0
|
|
3 3 NULL
|
|
NULL 4 0
|
|
NULL 2 NULL
|
|
explain extended
|
|
select a, oref, a in (select max(ie)
|
|
from t1 where oref=t2.oref group by grp) from t2;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t2 ALL NULL NULL NULL NULL 5
|
|
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 Using where; Using temporary; Using filesort
|
|
Warnings:
|
|
Note 1276 Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref`,<in_optimizer>(`test`.`t2`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = `test`.`t2`.`oref`) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t2`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie)
|
|
from t1 where oref=t2.oref group by grp)` from `test`.`t2`
|
|
explain extended
|
|
select a, oref from t2
|
|
where a in (select max(ie) from t1 where oref=t2.oref group by grp);
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t2 ALL NULL NULL NULL NULL 5 Using where
|
|
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 Using where; Using temporary; Using filesort
|
|
Warnings:
|
|
Note 1276 Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = `test`.`t2`.`oref`) group by `test`.`t1`.`grp` having (<cache>(`test`.`t2`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))
|
|
create table t3 (a int);
|
|
insert into t3 values (NULL), (NULL);
|
|
flush status;
|
|
select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
|
|
a in (select max(ie) from t1 where oref=4 group by grp)
|
|
0
|
|
0
|
|
show status like 'Handler_read_rnd_next';
|
|
Variable_name Value
|
|
Handler_read_rnd_next 11
|
|
select ' ^ This must show 11' Z;
|
|
Z
|
|
^ This must show 11
|
|
explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t3 ALL NULL NULL NULL NULL 2
|
|
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 Using where; Using temporary; Using filesort
|
|
Warnings:
|
|
Note 1003 select <in_optimizer>(`test`.`t3`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = 4) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t3`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3`
|
|
drop table t1, t2, t3;
|
|
create table t1 (a int, oref int, key(a));
|
|
insert into t1 values
|
|
(1, 1),
|
|
(1, NULL),
|
|
(2, 3),
|
|
(2, NULL),
|
|
(3, NULL);
|
|
create table t2 (a int, oref int);
|
|
insert into t2 values (1, 1), (2,2), (NULL, 3), (NULL, 4);
|
|
select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
|
|
oref a Z
|
|
1 1 1
|
|
2 2 0
|
|
3 NULL NULL
|
|
4 NULL 0
|
|
explain extended
|
|
select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t2 ALL NULL NULL NULL NULL 4
|
|
2 DEPENDENT SUBQUERY t1 index_subquery a a 5 func 2 Using index; Using where
|
|
Warnings:
|
|
Note 1276 Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 select `test`.`t2`.`oref` AS `oref`,`test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,<exists>(<index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on a checking NULL where (`test`.`t1`.`oref` = `test`.`t2`.`oref`)))) AS `Z` from `test`.`t2`
|
|
flush status;
|
|
select oref, a from t2 where a in (select a from t1 where oref=t2.oref);
|
|
oref a
|
|
1 1
|
|
show status like '%Handler_read_rnd_next';
|
|
Variable_name Value
|
|
Handler_read_rnd_next 5
|
|
delete from t2;
|
|
insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0);
|
|
flush status;
|
|
select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
|
|
oref a Z
|
|
0 NULL 0
|
|
0 NULL 0
|
|
0 NULL 0
|
|
0 NULL 0
|
|
show status like '%Handler_read%';
|
|
Variable_name Value
|
|
Handler_read_first 0
|
|
Handler_read_key 0
|
|
Handler_read_next 0
|
|
Handler_read_prev 0
|
|
Handler_read_rnd 0
|
|
Handler_read_rnd_next 29
|
|
select 'No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.' Z;
|
|
Z
|
|
No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.
|
|
drop table t1, t2;
|
|
create table t1 (a int, b int, primary key (a));
|
|
insert into t1 values (1,1), (3,1),(100,1);
|
|
create table t2 (a int, b int);
|
|
insert into t2 values (1,1),(2,1),(NULL,1),(NULL,0);
|
|
select a,b, a in (select a from t1 where t1.b = t2.b) Z from t2 ;
|
|
a b Z
|
|
1 1 1
|
|
2 1 0
|
|
NULL 1 NULL
|
|
NULL 0 0
|
|
drop table t1, t2;
|
|
create table t1 (a int, b int, key(a));
|
|
insert into t1 values
|
|
(0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9);
|
|
create table t2 like t1;
|
|
insert into t2 select * from t1;
|
|
update t2 set b=1;
|
|
create table t3 (a int, oref int);
|
|
insert into t3 values (1, 1), (NULL,1), (NULL,0);
|
|
select a, oref,
|
|
t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z
|
|
from t3;
|
|
a oref Z
|
|
1 1 1
|
|
NULL 1 NULL
|
|
NULL 0 0
|
|
explain extended
|
|
select a, oref,
|
|
t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z
|
|
from t3;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 PRIMARY t3 ALL NULL NULL NULL NULL 3
|
|
2 DEPENDENT SUBQUERY t1 ref_or_null a a 5 func 4 Using where
|
|
2 DEPENDENT SUBQUERY t2 ref a a 5 test.t1.b 1 Using where
|
|
Warnings:
|
|
Note 1276 Field or reference 't3.oref' of SELECT #2 was resolved in SELECT #1
|
|
Note 1003 select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<in_optimizer>(`test`.`t3`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t2`.`b` = `test`.`t3`.`oref`) and trigcond(((<cache>(`test`.`t3`.`a`) = `test`.`t1`.`a`) or isnull(`test`.`t1`.`a`)))) having trigcond(<is_not_null_test>(`test`.`t1`.`a`)))) AS `Z` from `test`.`t3`
|
|
drop table t1, t2, t3;
|