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MDEV-28621: group by optimization incorrectly removing subquery where subject buried in a function

Browse source 
Workaround patch: Do not remove GROUP BY clause when it has
subquer(ies) in it.

remove_redundant_subquery_clauses() removes redundant GROUP BY clause
from queries in form:
  expr IN (SELECT no_aggregates GROUP BY ...)
  expr {CMP} {ALL|ANY|SOME} (SELECT no_aggregates GROUP BY ...)
This hits problems when the GROUP BY clause itself has subquer(y/ies).

This patch is just a workaround: it disables removal of GROUP BY clause
if the clause has one or more subqueries in it.

Tests:
- subselect_elimination.test has all known crashing cases.
- subselect4.result, insert_select.result are updated.
Note that in some cases results of SELECT are changed too (not just
EXPLAINs). These are caused by non-deterministic SQL: when running a
query like:

  x > ANY( SELECT col1 FROM t1 GROUP BY constant_expression)

without removing the GROUP BY, the executor is free to pick the value
of t1.col1 from any row in the GROUP BY group (denote it $COL1_VAL).
Then, it computes x > ANY(SELECT $COL1_VAL).

When running the same query and removing the GROUP BY:

   x > ANY( SELECT col1 FROM t1)

the executor will actually check all rows of t1.
This commit is contained in:
Sergei Petrunia 2024-05-07 14:10:35 +03:00 • committed by Sergei Golubchik
parent ec6aa9ac42
commit 40b3525fcc
5 changed files with 599 additions and 65 deletions

8
mysql-test/main/insert_select.result
View file

@ -973,7 +973,6 @@ select * from t1;
a
3
1
2
delete from t1;
insert into t1 values (3), (1);
insert into t1
@ -984,8 +983,6 @@ select * from t1;
a
3
1
3
2
delete from t1;
insert into t1 values (3), (1);
insert into t1
@ -996,6 +993,7 @@ select * from t1;
a
3
1
3
2
delete from t1;
insert into t1 values (3), (1);
@ -1022,7 +1020,6 @@ select * from t1;
a
3
1
2
delete from t1;
insert into t1 values (3), (1);
execute stmt;
@ -1030,7 +1027,6 @@ select * from t1;
a
3
1
2
delete from t1;
insert into t1 values (3), (1);
delete from t1
@ -1040,6 +1036,8 @@ group by (select * from (select a from t1) dt
where a = 1)));
select * from t1;
a
3
1
deallocate prepare stmt;
drop table t1,t2,t3;
#

74
mysql-test/main/subselect4.result
View file

@ -2979,34 +2979,31 @@ where a >= any (select b from t2 group by (select c from t3 where c = 1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 100.00
3 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <nop>(<in_optimizer>(`test`.`t1`.`a`,(/* select#2 */ select min(`test`.`t2`.`b`) from `test`.`t2`) <= <cache>(`test`.`t1`.`a`)))
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <nop>(<in_optimizer>(`test`.`t1`.`a`,<min>(/* select#2 */ select `test`.`t2`.`b` from `test`.`t2` group by (/* select#3 */ select `test`.`t3`.`c` from `test`.`t3` where `test`.`t3`.`c` = 1)) <= <cache>(`test`.`t1`.`a`)))
select a from t1
where a >= any (select b from t2 group by (select c from t3 where c = 1));
a
3
2
prepare stmt from "select a from t1
where a >= any (select b from t2 group by (select c from t3 where c = 1))";
execute stmt;
a
3
2
execute stmt;
a
3
2
deallocate prepare stmt;
explain extended select a from t1
where a <= all (select b from t2 group by (select c from t3 where c = 1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 100.00
3 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <not>(<in_optimizer>(`test`.`t1`.`a`,(/* select#2 */ select min(`test`.`t2`.`b`) from `test`.`t2`) < <cache>(`test`.`t1`.`a`)))
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <not>(<in_optimizer>(`test`.`t1`.`a`,<min>(/* select#2 */ select `test`.`t2`.`b` from `test`.`t2` group by (/* select#3 */ select `test`.`t3`.`c` from `test`.`t3` where `test`.`t3`.`c` = 1)) < <cache>(`test`.`t1`.`a`)))
select a from t1
where a <= all (select b from t2 group by (select c from t3 where c = 1));
a
3
1
2
explain extended select a from t1
@ -3014,13 +3011,12 @@ where a >= any (select b from t2 group by 1 + (select c from t3 where c = 1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 100.00
3 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <nop>(<in_optimizer>(`test`.`t1`.`a`,(/* select#2 */ select min(`test`.`t2`.`b`) from `test`.`t2`) <= <cache>(`test`.`t1`.`a`)))
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where <nop>(<in_optimizer>(`test`.`t1`.`a`,<min>(/* select#2 */ select `test`.`t2`.`b` from `test`.`t2` group by 1 + (/* select#3 */ select `test`.`t3`.`c` from `test`.`t3` where `test`.`t3`.`c` = 1)) <= <cache>(`test`.`t1`.`a`)))
select a from t1
where a >= any (select b from t2 group by 1 + (select c from t3 where c = 1));
a
3
2
drop table t1,t2,t3;
#
# MDEV-29139: Redundant IN/ALL/ANY predicand in GROUP BY clause of
@ -3040,8 +3036,10 @@ group by (select a from t1 where a = 1) in (select d from t4));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00
2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00
4 SUBQUERY t4 ALL NULL NULL NULL NULL 2 100.00 Using where
3 SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where 1
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <in_optimizer>(1,exists(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null))) limit 1))
select b from t2
where exists (select c from t3
group by (select a from t1 where a = 1) in (select d from t4));
@ -3067,8 +3065,10 @@ any (select d from t4));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00
2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00
4 SUBQUERY t4 ALL NULL NULL NULL NULL 2 100.00 Using where
3 SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where 1
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <in_optimizer>(1,exists(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <nop>(<expr_cache><(/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)>(<in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) >= `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null))))) limit 1))
select b from t2
where exists (select c from t3
group by (select a from t1 where a = 1) >=
@ -3083,8 +3083,10 @@ all (select d from t4));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00
2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00
4 SUBQUERY t4 ALL NULL NULL NULL NULL 2 100.00 Using where
3 SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where 1
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <in_optimizer>(1,exists(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <not>(<expr_cache><(/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)>(<in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) >= `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null))))) limit 1))
select b from t2
where exists (select c from t3
group by (select a from t1 where a = 1) <
@ -3096,16 +3098,17 @@ explain extended select b from t2
where b in (select c from t3
group by (select a from t1 where a = 1) in (select d from t4));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1 100.00
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 test.t2.b 1 100.00
2 MATERIALIZED t3 ALL NULL NULL NULL NULL 2 100.00
4 SUBQUERY t4 ALL NULL NULL NULL NULL 2 100.00 Using where
3 SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`b` AS `b` from `test`.`t2` semi join (`test`.`t3`) where 1
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from <materialize> (/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null)))) join `test`.`t2` where `<subquery2>`.`c` = `test`.`t2`.`b`
select b from t2
where b in (select c from t3
group by (select a from t1 where a = 1) in (select d from t4));
b
2
explain extended select b from t2
where b >= any (select c from t3
group by (select a from t1 where a = 1) in
@ -3113,30 +3116,33 @@ group by (select a from t1 where a = 1) in
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where
2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00
4 SUBQUERY t4 ALL NULL NULL NULL NULL 2 100.00 Using where
3 SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <nop>(<in_optimizer>(`test`.`t2`.`b`,(/* select#2 */ select min(`test`.`t3`.`c`) from `test`.`t3`) <= <cache>(`test`.`t2`.`b`)))
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <nop>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null)))) <= <cache>(`test`.`t2`.`b`)))
select b from t2
where b >= any (select c from t3
group by (select a from t1 where a = 1) in
(select d from t4));
b
explain extended select b from t2
where b <= all (select c from t3
group by (select a from t1 where a = 1) in
(select d from t4));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where
2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00
4 SUBQUERY t4 ALL NULL NULL NULL NULL 2 100.00 Using where
3 SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <not>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3` group by <in_optimizer>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1),<exists>(/* select#4 */ select `test`.`t4`.`d` from `test`.`t4` where trigcond(<cache>((/* select#3 */ select `test`.`t1`.`a` from `test`.`t1` where `test`.`t1`.`a` = 1)) = `test`.`t4`.`d` or `test`.`t4`.`d` is null) having trigcond(`test`.`t4`.`d` is null)))) < <cache>(`test`.`t2`.`b`)))
select b from t2
where b <= all (select c from t3
group by (select a from t1 where a = 1) in
(select d from t4));
b
3
2
explain extended select b from t2
where b <= all (select c from t3
group by (select a from t1 where a = 1) in
(select d from t4));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where
2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <not>(<in_optimizer>(`test`.`t2`.`b`,<min>(/* select#2 */ select `test`.`t3`.`c` from `test`.`t3`) < <cache>(`test`.`t2`.`b`)))
select b from t2
where b <= all (select c from t3
group by (select a from t1 where a = 1) in
(select d from t4));
b
2
drop table t1,t2,t3,t4;
# End of 10.3 tests
#

268
mysql-test/main/subselect_elimination.result Normal file
View file

@ -0,0 +1,268 @@
#
# MDEV-28621 group by optimization incorrectly removing subquery where
# subject buried in a function
#
CREATE TABLE t1 (i int) ;
INSERT INTO t1 VALUES (1),(2),(3);
SELECT 1 FROM t1
WHERE i in
( SELECT a+1
FROM
(SELECT (SELECT i FROM (SELECT 1 FROM t1) dt) AS a FROM t1) dt2
GROUP BY a
);
ERROR 21000: Subquery returns more than 1 row
DROP TABLE t1;
create table t1 (a int, b int, c int);
insert into t1 select seq, seq, seq from seq_1_to_10;
create table t2 as select * from t1;
create table t20 as select * from t1;
create table t21 as select * from t1;
create table t3 as select * from t1;
select a, a in
(
select
(
select max(c) from t20 where t20.a<=t2.a
) as SUBQ1 from t2 group by SUBQ1+1
) as COL
from t1;
a COL
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 1
create view v2 as
select
a, b,
(select max(c) from t20 where t20.a<=t2.a) as SUBQ1,
(select max(c) from t21 where t21.a<=t2.a) as SUBQ2
from t2;
# test partial elimination
explain
select
a,
a in (select a from v2 where a>3 and v2.SUBQ2>=0 group by v2.SUBQ1, v2.SUBQ2)
from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
5 DEPENDENT SUBQUERY t21 ALL NULL NULL NULL NULL 10 Using where
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
# test buried subselects in group by clause
select a, a in
(
select
(
select max(c) from t20 where t20.a<=t2.a
)*2 as SUBQ1 from t2 group by SUBQ1+1
) as COL
from t1;
a COL
1 0
2 1
3 0
4 1
5 0
6 1
7 0
8 1
9 0
10 1
drop view v2;
drop table t1, t2, t20, t21, t3;
# Testcase from MDEV-32311
SELECT (
( WITH x ( x ) AS
(SELECT ( SELECT 'x' UNION SELECT 'x' ) FROM ( SELECT ( 'x' ) ) x)
SELECT x FROM x
WHERE x IN ( ( SELECT 'x' AND x GROUP BY x ) )
)
) AS SUBQ;
SUBQ
x
# MDEV-32390:
CREATE TABLE t0 ( c43 DECIMAL ( 31 ) DEFAULT ( 45 ) ) ;
INSERT INTO t0 VALUES ( 13 ) , ( 29 ) ;
ALTER TABLE t0 ADD COLUMN c24 INT AFTER c43 ;
INSERT INTO t0 VALUES ( DEFAULT , DEFAULT ) , ( DEFAULT , DEFAULT ) ;
SELECT t1 . c22 AS c9 FROM ( SELECT ( SELECT + EXISTS ( SELECT -128 AS c29 ) <<
LOCATE ( t0 . c43 , t0 . c24 <= t0 . c24 NOT BETWEEN 4642475734208631537 AND
-108 , NULLIF ( 57 , -8 ) SOUNDS LIKE TRIM( TRAILING FROM 6107036197732405580 )
) - t0 . c43 AS c57 FROM t0 LIMIT 1 ) AS c22 FROM t0 ) AS t1 HAVING TRIM( CASE
t1 . c22 WHEN -16 THEN RAND ( ) % HEX ( t1 . c22 ) - SUBSTRING_INDEX ( t1 . c22,
':A9SEZxtjN,fKN*zR' , 'V*vhJb}&c%Op,[T[S,j`F9NDsK;\'8 4;m"
P,ce}1r"3ID1DN' ) >> NULLIF ( t1 . c22 , -95 ) ELSE -2 END IS TRUE
FROM t1 . c22 >= EXISTS ( SELECT t2 . c57 AS c59 FROM ( SELECT CASE c24 WHEN
-103 THEN 85 ELSE 22 END IS TRUE AS c57 FROM t0 ) AS t2 WHERE MOD ( 64 , 46 ) =
CONVERT ( 73 , BINARY ) % RAND ( ) IS NOT NULL = -65 GROUP BY c57 , c22 , c22
WINDOW w0 AS ( PARTITION BY t2 . c57 ) ) & PI ( ) ) ;
c9
DROP TABLE t0;
# MDEV-32309
SELECT
( WITH x ( x ) AS
(
WITH x ( x ) AS ( SELECT 1 ) SELECT ( SELECT x ) FROM x
)
SELECT x FROM x WHERE x IN ( SELECT NULL GROUP BY x )
) as col1 ;
col1
NULL
# MDEV-32391
CREATE TABLE t0 ( c15 INT , c33 INT ) engine=innodb;
INSERT INTO t0 ( c15 ) WITH t1 AS ( SELECT SQRT ( 123 ) NOT
REGEXP MOD ( 91 , -121 ) = ALL ( SELECT c15 AS c33 FROM t0 ) AS c49 FROM t0 )
SELECT t1 . c49 IS UNKNOWN AS c59 FROM t1 CROSS JOIN t0 AS t2
WHERE t1 . c49 = + EXISTS ( SELECT -5839312620871436105 AS c17 GROUP BY c49 )
BETWEEN -109 AND CHAR_LENGTH ( 2694839150676403988 ) - - LOWER ( -13 ) ;
DROP TABLE t0;
# MDEV-28620
CREATE TABLE t1 ( a int);
INSERT INTO t1 VALUES (1),(2);
SELECT EXISTS
( SELECT 1 FROM t1 GROUP BY 1 IN (SELECT a FROM t1)
ORDER BY a + (SELECT 1 FROM t1 WHERE (1,2) NOT IN (SELECT 1,0))
) as SUBQ;
ERROR 21000: Subquery returns more than 1 row
DROP TABLE t1;
# MDEV-30842 Item_subselect::get_cache_parameters and UBSAN member
# access within null pointer
CREATE TABLE x (x INT) ENGINE=InnoDB;
INSERT INTO x (x) VALUES (0);
INSERT INTO x (x) VALUES (x IN (SELECT (SELECT x FROM (SELECT x FROM
(SELECT 0 IN (SELECT x=0 FROM (SELECT x FROM (SELECT (SELECT (SELECT (SELECT
(SELECT 0 AS x) FROM x AS x) IN (SELECT 0 AS x) AS x) FROM x AS x) IN
(SELECT x WHERE x=0) AS x FROM x AS x) AS x) AS x GROUP BY x) AS x FROM x) AS x)
AS x) IN (SELECT 0 AS x) AS x FROM x));
ERROR HY000: Table 'x' is specified twice, both as a target for 'INSERT' and as a separate source for data
DROP TABLE x;
# MDEV-28622: Item_subselect eliminated flag set but Item still
# evaluated/used.
CREATE TABLE t1 ( a int) ;
CREATE VIEW v1 (i) AS SELECT EXISTS(SELECT 1) FROM t1;
SELECT 1 FROM v1 WHERE i NOT IN (SELECT i = 0 FROM v1 WHERE i = -1 GROUP BY i);
1
DROP TABLE t1;
DROP VIEW v1;
CREATE TABLE t(c1 INT);
SELECT 0
WHERE 0 IN
(
SELECT 0 FROM
(
SELECT 0 IN
(
SELECT
(
SELECT c1 FROM t
)
) AS c
FROM t
) AS dt
WHERE c GROUP BY c
);
0
DROP TABLE t;
create table t1 (a int, b int, c int);
insert into t1 select seq, seq, seq from seq_1_to_10;
create table t2 as select * from t1;
create table t20 as select * from t1;
create table t3 as select * from t1;
create view v2 as
select
a, b, (select max(c) from t20 where t20.a<=t2.a) as SUBQ1
from t2;
explain
select
a, a in (select a from v2 where a>3 group by v2.SUBQ1)
from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
prepare s from '
explain
select
a, a in (select a from v2 where a>3 group by v2.SUBQ1)
from t1';
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
prepare s from '
explain
select
a, a in (select a from v2 where a>3 and SUBQ1+1 group by v2.SUBQ1)
from t1';
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
execute s;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
create procedure p1()
begin
explain
select
a, a in (select a from v2 where a>3 group by v2.SUBQ1)
from t1;
end//
create procedure p2()
begin
explain
select
a, a in (select a from v2 where a>3 and SUBQ1+1 group by v2.SUBQ1)
from t1;
end//
call p1();
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
call p1();
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
call p2();
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
call p2();
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 10
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 10 Using where; Using temporary
4 DEPENDENT SUBQUERY t20 ALL NULL NULL NULL NULL 10 Using where
drop procedure p1;
drop procedure p2;
drop view v2;
drop table t1,t2,t3,t20;
# end of 10.4 tests

242
mysql-test/main/subselect_elimination.test Normal file
View file

@ -0,0 +1,242 @@
--source include/have_innodb.inc
--source include/have_sequence.inc
--echo #
--echo # MDEV-28621 group by optimization incorrectly removing subquery where
--echo # subject buried in a function
--echo #
CREATE TABLE t1 (i int) ;
INSERT INTO t1 VALUES (1),(2),(3);
--error ER_SUBQUERY_NO_1_ROW
SELECT 1 FROM t1
WHERE i in
( SELECT a+1
FROM
(SELECT (SELECT i FROM (SELECT 1 FROM t1) dt) AS a FROM t1) dt2
GROUP BY a
);
DROP TABLE t1;
create table t1 (a int, b int, c int);
insert into t1 select seq, seq, seq from seq_1_to_10;
create table t2 as select * from t1;
create table t20 as select * from t1;
create table t21 as select * from t1;
create table t3 as select * from t1;
select a, a in
(
select
(
select max(c) from t20 where t20.a<=t2.a
) as SUBQ1 from t2 group by SUBQ1+1
) as COL
from t1;
create view v2 as
select
a, b,
(select max(c) from t20 where t20.a<=t2.a) as SUBQ1,
(select max(c) from t21 where t21.a<=t2.a) as SUBQ2
from t2;
--echo # test partial elimination
explain
select
a,
a in (select a from v2 where a>3 and v2.SUBQ2>=0 group by v2.SUBQ1, v2.SUBQ2)
from t1;
--echo # test buried subselects in group by clause
select a, a in
(
select
(
select max(c) from t20 where t20.a<=t2.a
)*2 as SUBQ1 from t2 group by SUBQ1+1
) as COL
from t1;
drop view v2;
drop table t1, t2, t20, t21, t3;
--echo # Testcase from MDEV-32311
# some warning duplicated using ps-protocol
--disable_warnings
SELECT (
( WITH x ( x ) AS
(SELECT ( SELECT 'x' UNION SELECT 'x' ) FROM ( SELECT ( 'x' ) ) x)
SELECT x FROM x
WHERE x IN ( ( SELECT 'x' AND x GROUP BY x ) )
)
) AS SUBQ;
--enable_warnings
--echo # MDEV-32390:
CREATE TABLE t0 ( c43 DECIMAL ( 31 ) DEFAULT ( 45 ) ) ;
INSERT INTO t0 VALUES ( 13 ) , ( 29 ) ;
ALTER TABLE t0 ADD COLUMN c24 INT AFTER c43 ;
INSERT INTO t0 VALUES ( DEFAULT , DEFAULT ) , ( DEFAULT , DEFAULT ) ;
SELECT t1 . c22 AS c9 FROM ( SELECT ( SELECT + EXISTS ( SELECT -128 AS c29 ) <<
LOCATE ( t0 . c43 , t0 . c24 <= t0 . c24 NOT BETWEEN 4642475734208631537 AND
-108 , NULLIF ( 57 , -8 ) SOUNDS LIKE TRIM( TRAILING FROM 6107036197732405580 )
) - t0 . c43 AS c57 FROM t0 LIMIT 1 ) AS c22 FROM t0 ) AS t1 HAVING TRIM( CASE
t1 . c22 WHEN -16 THEN RAND ( ) % HEX ( t1 . c22 ) - SUBSTRING_INDEX ( t1 . c22,
':A9SEZxtjN,fKN*zR' , 'V*vhJb}&c%Op,[T[S,j`F9NDsK;\'8 4;m"
P,ce}1r"3ID1DN' ) >> NULLIF ( t1 . c22 , -95 ) ELSE -2 END IS TRUE
FROM t1 . c22 >= EXISTS ( SELECT t2 . c57 AS c59 FROM ( SELECT CASE c24 WHEN
-103 THEN 85 ELSE 22 END IS TRUE AS c57 FROM t0 ) AS t2 WHERE MOD ( 64 , 46 ) =
CONVERT ( 73 , BINARY ) % RAND ( ) IS NOT NULL = -65 GROUP BY c57 , c22 , c22
WINDOW w0 AS ( PARTITION BY t2 . c57 ) ) & PI ( ) ) ;
DROP TABLE t0;
--echo # MDEV-32309
SELECT
( WITH x ( x ) AS
(
WITH x ( x ) AS ( SELECT 1 ) SELECT ( SELECT x ) FROM x
)
SELECT x FROM x WHERE x IN ( SELECT NULL GROUP BY x )
) as col1 ;
--echo # MDEV-32391
CREATE TABLE t0 ( c15 INT , c33 INT ) engine=innodb;
INSERT INTO t0 ( c15 ) WITH t1 AS ( SELECT SQRT ( 123 ) NOT
REGEXP MOD ( 91 , -121 ) = ALL ( SELECT c15 AS c33 FROM t0 ) AS c49 FROM t0 )
SELECT t1 . c49 IS UNKNOWN AS c59 FROM t1 CROSS JOIN t0 AS t2
WHERE t1 . c49 = + EXISTS ( SELECT -5839312620871436105 AS c17 GROUP BY c49 )
BETWEEN -109 AND CHAR_LENGTH ( 2694839150676403988 ) - - LOWER ( -13 ) ;
DROP TABLE t0;
--echo # MDEV-28620
CREATE TABLE t1 ( a int);
INSERT INTO t1 VALUES (1),(2);
--error ER_SUBQUERY_NO_1_ROW
SELECT EXISTS
( SELECT 1 FROM t1 GROUP BY 1 IN (SELECT a FROM t1)
ORDER BY a + (SELECT 1 FROM t1 WHERE (1,2) NOT IN (SELECT 1,0))
) as SUBQ;
DROP TABLE t1;
--echo # MDEV-30842 Item_subselect::get_cache_parameters and UBSAN member
--echo # access within null pointer
CREATE TABLE x (x INT) ENGINE=InnoDB;
INSERT INTO x (x) VALUES (0);
--error ER_UPDATE_TABLE_USED
INSERT INTO x (x) VALUES (x IN (SELECT (SELECT x FROM (SELECT x FROM
(SELECT 0 IN (SELECT x=0 FROM (SELECT x FROM (SELECT (SELECT (SELECT (SELECT
(SELECT 0 AS x) FROM x AS x) IN (SELECT 0 AS x) AS x) FROM x AS x) IN
(SELECT x WHERE x=0) AS x FROM x AS x) AS x) AS x GROUP BY x) AS x FROM x) AS x)
AS x) IN (SELECT 0 AS x) AS x FROM x));
DROP TABLE x;
--echo # MDEV-28622: Item_subselect eliminated flag set but Item still
--echo # evaluated/used.
CREATE TABLE t1 ( a int) ;
CREATE VIEW v1 (i) AS SELECT EXISTS(SELECT 1) FROM t1;
SELECT 1 FROM v1 WHERE i NOT IN (SELECT i = 0 FROM v1 WHERE i = -1 GROUP BY i);
DROP TABLE t1;
DROP VIEW v1;
CREATE TABLE t(c1 INT);
SELECT 0
WHERE 0 IN
(
SELECT 0 FROM
(
SELECT 0 IN
(
SELECT
(
SELECT c1 FROM t
)
) AS c
FROM t
) AS dt
WHERE c GROUP BY c
);
DROP TABLE t;
create table t1 (a int, b int, c int);
insert into t1 select seq, seq, seq from seq_1_to_10;
create table t2 as select * from t1;
create table t20 as select * from t1;
create table t3 as select * from t1;
create view v2 as
select
a, b, (select max(c) from t20 where t20.a<=t2.a) as SUBQ1
from t2;
explain
select
a, a in (select a from v2 where a>3 group by v2.SUBQ1)
from t1;
prepare s from '
explain
select
a, a in (select a from v2 where a>3 group by v2.SUBQ1)
from t1';
execute s;
execute s;
execute s;
prepare s from '
explain
select
a, a in (select a from v2 where a>3 and SUBQ1+1 group by v2.SUBQ1)
from t1';
execute s;
execute s;
execute s;
delimiter //;
create procedure p1()
begin
explain
select
a, a in (select a from v2 where a>3 group by v2.SUBQ1)
from t1;
end//
create procedure p2()
begin
explain
select
a, a in (select a from v2 where a>3 and SUBQ1+1 group by v2.SUBQ1)
from t1;
end//
delimiter ;//
call p1();
call p1();
call p2();
call p2();
drop procedure p1;
drop procedure p2;
drop view v2;
drop table t1,t2,t3,t20;
--echo # end of 10.4 tests

72
sql/sql_select.cc
View file

@ -671,37 +671,57 @@ void remove_redundant_subquery_clauses(st_select_lex *subq_select_lex)
if (subq_select_lex->group_list.elements &&
!subq_select_lex->with_sum_func && !subq_select_lex->join->having)
{
/*
Temporary workaround for MDEV-28621: Do not remove GROUP BY expression
if it has any subqueries in it.
*/
bool have_subquery= false;
for (ORDER *ord= subq_select_lex->group_list.first; ord; ord= ord->next)
{
/*
Do not remove the item if it is used in select list and then referred
from GROUP BY clause by its name or number. Example:
select (select ... ) as SUBQ ... group by SUBQ
Here SUBQ cannot be removed.
*/
if (!ord->in_field_list)
if ((*ord->item)->with_subquery())
{
(*ord->item)->walk(&Item::eliminate_subselect_processor, FALSE, NULL);
/*
Remove from the JOIN::all_fields list any reference to the elements
of the eliminated GROUP BY list unless it is 'in_field_list'.
This is needed in order not to confuse JOIN::make_aggr_tables_info()
when it constructs different structure for execution phase.
*/
List_iterator<Item> li(subq_select_lex->join->all_fields);
Item *item;
while ((item= li++))
{
if (item == *ord->item)
li.remove();
}
have_subquery= true;
break;
}
}
subq_select_lex->join->group_list= NULL;
subq_select_lex->group_list.empty();
DBUG_PRINT("info", ("GROUP BY removed"));
if (!have_subquery)
{
for (ORDER *ord= subq_select_lex->group_list.first; ord; ord= ord->next)
{
/*
Do not remove the item if it is used in select list and then referred
from GROUP BY clause by its name or number. Example:
select (select ... ) as SUBQ ... group by SUBQ
Here SUBQ cannot be removed.
*/
if (!ord->in_field_list)
{
/*
Not necessary due to workaround for MDEV-28621:
(*ord->item)->walk(&Item::eliminate_subselect_processor, FALSE, NULL);
*/
/*
Remove from the JOIN::all_fields list any reference to the elements
of the eliminated GROUP BY list unless it is 'in_field_list'.
This is needed in order not to confuse JOIN::make_aggr_tables_info()
when it constructs different structure for execution phase.
*/
List_iterator<Item> li(subq_select_lex->join->all_fields);
Item *item;
while ((item= li++))
{
if (item == *ord->item)
li.remove();
}
}
}
subq_select_lex->join->group_list= NULL;
subq_select_lex->group_list.empty();
DBUG_PRINT("info", ("GROUP BY removed"));
}
}
/*