drop table if exists t0, t1, t2, t3, t4, t5, t6;
drop view if exists v1, v2;
SET @save_optimizer_switch=@@optimizer_switch;
SET optimizer_switch='outer_join_with_cache=off';
create table t1 (a int);
insert into t1 values (0),(1),(2),(3);
create table t0 as select * from t1;
create table t2 (a int primary key, b int) 
as select a, a as b from t1 where a in (1,2);
create table t3 (a int primary key, b int) 
as select a, a as b from t1 where a in (1,3);
# This will be  eliminated:
explain select t1.a from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain extended select t1.a from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	
Warnings:
Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 1
select t1.a from t1 left join t2 on t2.a=t1.a;
a
0
1
2
3
# This will not be eliminated as t2.b is in in select list:
explain select * from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
# This will not be eliminated as t2.b is in in order list:
explain select t1.a from t1 left join t2 on t2.a=t1.a order by t2.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
# This will not be eliminated as t2.b is in group list:
explain select t1.a from t1 left join t2 on t2.a=t1.a group by t2.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
# This will not be eliminated as t2.b is in the WHERE
explain select t1.a from t1 left join t2 on t2.a=t1.a where t2.b < 3 or t2.b is null;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
# Elimination of multiple tables:
explain select t1.a from t1 left join (t2 join t3) on t2.a=t1.a and t3.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
# Elimination of multiple tables (2):
explain select t1.a from t1 left join (t2 join t3 on t2.b=t3.b) on t2.a=t1.a and t3.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
# Elimination when done within an outer join nest:
explain extended
select t0.*
from
t0 left join (t1 left join (t2 join t3 on t2.b=t3.b) on t2.a=t1.a and
t3.a=t1.a) on t0.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	4	100.00	
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	Using where
Warnings:
Note	1003	select `test`.`t0`.`a` AS `a` from `test`.`t0` left join (`test`.`t1`) on(`test`.`t1`.`a` = `test`.`t0`.`a`) where 1
# Elimination with aggregate functions
explain select count(*) from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain select count(1) from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain select count(1) from t1 left join t2 on t2.a=t1.a group by t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
This must not use elimination:
explain select count(1) from t1 left join t2 on t2.a=t1.a group by t2.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using index
drop table t0, t1, t2, t3;
create table t0 ( id integer, primary key (id));
create table t1 (
id integer,
attr1 integer,
primary key (id),
key (attr1)
);
create table t2 (
id integer,
attr2 integer,
fromdate date,
primary key (id, fromdate),
key (attr2,fromdate)
);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
insert into t0 select A.id + 10*B.id from t0 A, t0 B where B.id > 0;
insert into t1 select id, id from t0;
insert into t2 select id, id, date_add('2009-06-22', interval id day) from t0;
insert into t2 select id, id+1, date_add('2008-06-22', interval id day) from t0;
create view v1 as
select 
f.id, a1.attr1, a2.attr2
from 
t0 f 
left join t1 a1 on a1.id=f.id
left join t2 a2 on a2.id=f.id and 
a2.fromdate=(select MAX(fromdate) from
t2 where id=a2.id);
create view v2 as
select 
f.id, a1.attr1, a2.attr2
from 
t0 f 
left join t1 a1 on a1.id=f.id
left join t2 a2 on a2.id=f.id and 
a2.fromdate=(select MAX(fromdate) from
t2 where id=f.id);
This should use one table:
explain select id from v1 where id=2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	f	const	PRIMARY	PRIMARY	4	const	1	Using index
This should use one table:
explain extended select id from v1 where id in (1,2,3,4);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	f	range	PRIMARY	PRIMARY	4	NULL	4	100.00	Using where; Using index
Warnings:
Note	1276	Field or reference 'test.a2.id' of SELECT #3 was resolved in SELECT #2
Note	1003	/* select#1 */ select `f`.`id` AS `id` from `test`.`t0` `f` where `f`.`id` in (1,2,3,4)
This should use facts and a1 tables:
explain extended select id from v1 where attr1 between 12 and 14;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition
1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a1.id	1	100.00	Using index
Warnings:
Note	1276	Field or reference 'test.a2.id' of SELECT #3 was resolved in SELECT #2
Note	1003	/* select#1 */ select `f`.`id` AS `id` from `test`.`t0` `f` join `test`.`t1` `a1` where `f`.`id` = `a1`.`id` and `a1`.`attr1` between 12 and 14
This should use facts, a2 and its subquery:
explain extended select id from v1 where attr2 between 12 and 14;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	a2	range	PRIMARY,attr2	attr2	5	NULL	4	100.00	Using index condition; Using where
1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a2.id	1	100.00	Using index
3	DEPENDENT SUBQUERY	t2	ref	PRIMARY	PRIMARY	4	test.a2.id	2	100.00	Using index
Warnings:
Note	1276	Field or reference 'test.a2.id' of SELECT #3 was resolved in SELECT #2
Note	1003	/* select#1 */ select `f`.`id` AS `id` from `test`.`t0` `f` join `test`.`t2` `a2` where `f`.`id` = `a2`.`id` and `a2`.`attr2` between 12 and 14 and `a2`.`fromdate` = <expr_cache><`a2`.`id`>((/* select#3 */ select max(`test`.`t2`.`fromdate`) from `test`.`t2` where `test`.`t2`.`id` = `a2`.`id`))
This should use one table:
explain select id from v2 where id=2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	f	const	PRIMARY	PRIMARY	4	const	1	Using index
This should use one table:
explain extended select id from v2 where id in (1,2,3,4);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	f	range	PRIMARY	PRIMARY	4	NULL	4	100.00	Using where; Using index
Warnings:
Note	1276	Field or reference 'test.f.id' of SELECT #3 was resolved in SELECT #2
Note	1003	/* select#1 */ select `f`.`id` AS `id` from `test`.`t0` `f` where `f`.`id` in (1,2,3,4)
This should use facts and a1 tables:
explain extended select id from v2 where attr1 between 12 and 14;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition
1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a1.id	1	100.00	Using index
Warnings:
Note	1276	Field or reference 'test.f.id' of SELECT #3 was resolved in SELECT #2
Note	1003	/* select#1 */ select `f`.`id` AS `id` from `test`.`t0` `f` join `test`.`t1` `a1` where `f`.`id` = `a1`.`id` and `a1`.`attr1` between 12 and 14
This should use facts, a2 and its subquery:
explain extended select id from v2 where attr2 between 12 and 14;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	a2	range	PRIMARY,attr2	attr2	5	NULL	4	100.00	Using index condition
1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a2.id	1	100.00	Using where; Using index
3	DEPENDENT SUBQUERY	t2	ref	PRIMARY	PRIMARY	4	test.f.id	2	100.00	Using index
Warnings:
Note	1276	Field or reference 'test.f.id' of SELECT #3 was resolved in SELECT #2
Note	1003	/* select#1 */ select `f`.`id` AS `id` from `test`.`t0` `f` join `test`.`t2` `a2` where `f`.`id` = `a2`.`id` and `a2`.`attr2` between 12 and 14 and `a2`.`fromdate` = <expr_cache><`f`.`id`>((/* select#3 */ select max(`test`.`t2`.`fromdate`) from `test`.`t2` where `test`.`t2`.`id` = `f`.`id`))
drop view v1, v2;
drop table t0, t1, t2;
create table t1 (a int);
insert into t1 values (0),(1),(2),(3);
create table t2 (pk1 int, pk2 int, pk3 int, col int, primary key(pk1, pk2, pk3));
insert into t2 select a,a,a,a from t1;
This must use only t1:
explain select t1.* from t1 left join t2 on t2.pk1=t1.a and 
t2.pk2=t2.pk1+1 and
t2.pk3=t2.pk2+1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
This must use only t1:
explain select t1.* from t1 left join t2 on t2.pk1=t1.a and 
t2.pk3=t2.pk1+1 and
t2.pk2=t2.pk3+1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
This must use both:
explain select t1.* from t1 left join t2 on t2.pk1=t1.a and 
t2.pk3=t2.pk1+1 and
t2.pk2=t2.pk3+t2.col;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
This must use only t1:
explain select t1.* from t1 left join t2 on t2.pk2=t1.a and 
t2.pk1=t2.pk2+1 and
t2.pk3=t2.pk1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
drop table t1, t2;
create table t1 (pk int primary key, col int);
insert into t1 values (1,1),(2,2);
create table t2 like t1;
insert into t2 select * from t1;
create table t3 like t1;
insert into t3 select * from t1;
explain 
select t1.* from t1 left join ( t2 left join t3 on t3.pk=t2.col) on t2.col=t1.col;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
explain 
select t1.*, t2.* from t1 left join (t2 left join t3 on t3.pk=t2.col) on t2.pk=t1.col;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	Using where
explain select t1.* 
from 
t1 left join ( t2 left join t3 on t3.pk=t2.col or t3.pk=t2.col) 
on t2.col=t1.col or t2.col=t1.col;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
explain select t1.*, t2.* 
from 
t1 left join 
(t2 left join t3 on t3.pk=t2.col or t3.pk=t2.col) 
on t2.pk=t1.col or t2.pk=t1.col;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	Using where
drop table t1, t2, t3;
# 
# Check things that look like functional dependencies but really are not
# 
create table t1 (a char(10) character set latin1 collate latin1_general_ci primary key);
insert into t1 values ('foo');
insert into t1 values ('bar');
create table t2 (a char(10) character set latin1 collate latin1_general_cs primary key);
insert into t2 values ('foo');
insert into t2 values ('FOO');
this must not use table elimination:
explain select t1.* from t1 left join t2 on t2.a='foo' collate latin1_general_ci;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	index	NULL	PRIMARY	10	NULL	2	Using index
1	SIMPLE	t2	index	PRIMARY	PRIMARY	10	NULL	2	Using where; Using index
Warnings:
Note	1105	Cannot use key `PRIMARY` part[0] for lookup: `test`.`t2`.`a` of collation `latin1_general_cs` = "'foo' collate latin1_general_ci" of collation `latin1_general_ci`
this must not use table elimination:
explain select t1.* from t1 left join t2 on t2.a=t1.a collate latin1_general_ci;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	index	NULL	PRIMARY	10	NULL	2	Using index
1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	2	Range checked for each record (index map: 0x1)
Warnings:
Note	1105	Cannot use key `PRIMARY` part[0] for lookup: `test`.`t2`.`a` of collation `latin1_general_cs` = "`t1`.`a` collate latin1_general_ci" of collation `latin1_general_ci`
drop table t1,t2;
create table t1 (a int primary key);
insert into t1 values (1),(2);
create table t2 (a char(10) primary key);
insert into t2 values ('1'),('1.0');
this must not use table elimination:
explain select t1.* from t1 left join t2 on t2.a=1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	2	Using index
1	SIMPLE	t2	index	PRIMARY	PRIMARY	10	NULL	2	Using where; Using index
Warnings:
Note	1105	Cannot use key `PRIMARY` part[0] for lookup: `test`.`t2`.`a` of type `char` = "1" of type `int`
this must not use table elimination:
explain select t1.* from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	2	Using index
1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	2	Range checked for each record (index map: 0x1)
Warnings:
Note	1105	Cannot use key `PRIMARY` part[0] for lookup: `test`.`t2`.`a` of type `char` = "`t1`.`a`" of type `int`
drop table t1, t2;
create table t1 (a char(10) primary key);
insert into t1 values ('foo'),('bar');
create table t2 (a char(10), unique key(a(2)));
insert into t2 values
('foo'),('bar'),('boo'),('car'),('coo'),('par'),('doo'),('tar');
explain select t1.* from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	index	NULL	PRIMARY	10	NULL	2	Using index
1	SIMPLE	t2	eq_ref	a	a	3	test.t1.a	1	Using where
drop table t1, t2;
#
# check UPDATE/DELETE that look like they could be eliminated
#
create table t1 (a int primary key, b int);
insert into t1 values (1,1),(2,2),(3,3);
create table t2 like t1;
insert into t2 select * from t1;
update t1 left join t2 using (a) set t2.a=t2.a+100;
select * from t1;
a	b
1	1
2	2
3	3
select * from t2;
a	b
101	1
102	2
103	3
delete from t2;
insert into t2 select * from t1;
delete t2 from t1 left join t2 using (a);
select * from t1;
a	b
1	1
2	2
3	3
select * from t2;
a	b
drop table t1, t2;
#
# Tests with various edge-case ON expressions
#
create table t1 (a int, b int, c int, d int);
insert into t1 values (0,0,0,0),(1,1,1,1),(2,2,2,2),(3,3,3,3);
create table t2 (pk int primary key, b int) 
as select a as pk, a as b from t1 where a in (1,2);
create table t3 (pk1 int, pk2 int, b int, unique(pk1,pk2));
insert into t3 select a as pk1, a as pk2, a as b from t1 where a in (1,3);
explain select t1.a from t1 left join t2 on t2.pk=t1.a and t2.b<t1.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain select t1.a from t1 left join t2 on t2.pk=t1.a or t2.b<t1.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	2	Using where
explain select t1.a from t1 left join t2 on t2.b<t1.b or t2.pk=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	2	Using where
explain select t1.a from t1 left join t2 on t2.pk between 10 and 20;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	range	PRIMARY	PRIMARY	4	NULL	1	Using where; Using index
explain select t1.a from t1 left join t2 on t2.pk between 0.5 and 1.5;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using where; Using index
explain select t1.a from t1 left join t2 on t2.pk between 10 and 10;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain select t1.a from t1 left join t2 on t2.pk in (10);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain select t1.a from t1 left join t2 on t2.pk in (t1.a);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain select t1.a from t1 left join t2 on TRUE;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	index	NULL	PRIMARY	4	NULL	2	Using where; Using index
explain select t1.a from t1 left join t3 on t3.pk1=t1.a and t3.pk2 IS NULL;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t3	ref	pk1	pk1	10	test.t1.a,const	2	Using where; Using index
drop table t1,t2,t3;
#
# Multi-equality tests 
#
create table t1 (a int, b int, c int, d int);
insert into t1 values (0,0,0,0),(1,1,1,1),(2,2,2,2),(3,3,3,3);
create table t2 (pk int primary key, b int, c int);
insert into t2 select a,a,a from t1 where a in (1,2);
explain 
select t1.* 
from t1 left join t2 on t2.pk=t2.c and t2.b=t1.a and t1.a=t1.b and t2.c=t2.b
where t1.d=1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
explain 
select t1.* 
from 
t1 
left join 
t2 
on (t2.pk=t2.c and t2.b=t1.a and t1.a=t1.b and t2.c=t2.b) or
(t2.pk=t2.c and t2.b=t1.a and t1.a=t1.b and t2.c=t2.b) 
where t1.d=1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
#This can't be eliminated:
explain 
select t1.* 
from 
t1 
left join 
t2 
on (t2.pk=t2.c and t2.b=t1.a and               t2.c=t1.b) or
(t2.pk=t2.c and               t1.a=t1.b and t2.c=t1.b) 
where t1.d=1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using where
explain 
select t1.* 
from 
t1 
left join 
t2 
on (t2.pk=t2.c and t2.b=t1.a and t2.c=t1.b) or
(t2.pk=t2.c and               t2.c=t1.b) 
;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain 
select t1.* 
from t1 left join t2 on t2.pk=3 or t2.pk= 4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using where; Using index
explain 
select t1.* 
from t1 left join t2 on t2.pk=3 or t2.pk= 3;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
explain 
select t1.* 
from t1 left join t2 on (t2.pk=3 and t2.b=3) or (t2.pk= 4 and t2.b=3);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using where
drop table t1, t2;
#
# LPBUG#523593: Running RQG optimizer_no_subquery crashes MariaDB
#
CREATE TABLE t1 (
`pk` int(11) NOT NULL AUTO_INCREMENT,
`col_int_nokey` int(11) DEFAULT NULL,
`col_int_key` int(11) DEFAULT NULL,
`col_date_key` date DEFAULT NULL,
`col_date_nokey` date DEFAULT NULL,
`col_time_key` time DEFAULT NULL,
`col_time_nokey` time DEFAULT NULL,
`col_datetime_key` datetime DEFAULT NULL,
`col_datetime_nokey` datetime DEFAULT NULL,
`col_varchar_key` varchar(1) DEFAULT NULL,
`col_varchar_nokey` varchar(1) DEFAULT NULL,
PRIMARY KEY (`pk`),
KEY `col_int_key` (`col_int_key`),
KEY `col_date_key` (`col_date_key`),
KEY `col_time_key` (`col_time_key`),
KEY `col_datetime_key` (`col_datetime_key`),
KEY `col_varchar_key` (`col_varchar_key`,`col_int_key`)
);
CREATE TABLE t2 LIKE t1;
INSERT INTO t1 VALUES 
(10,7,8,NULL,NULL,'01:27:35','01:27:35','2002-02-26 06:14:37','2002-02-26 06:14:37','v','v'),
(11,1,9,'2006-06-14','2006-06-14','19:48:31','19:48:31','1900-01-01 00:00:00','1900-01-01 00:00:00','r','r');
INSERT INTO t2 SELECT * FROM t1;
SELECT table2.col_int_key AS field1 
FROM ( 
t2 AS table1 
RIGHT OUTER JOIN 
( 
( t1 AS table2 STRAIGHT_JOIN 
t1 AS table3 ON (
(table3.col_varchar_nokey = table2.col_varchar_key ) AND 
(table3.pk = table2.col_int_key)) 
)
) ON 
(
(table3.col_varchar_key = table2.col_varchar_key) OR 
(table3.col_int_key = table2.pk)
)
)
HAVING field1 < 216;
field1
DROP TABLE t1, t2;
#
# LPBUG#524025 Running RQG outer_join test leads to crash
#
CREATE TABLE t0 (
pk int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (pk)
);
CREATE TABLE t1 (
col_int int(11) DEFAULT NULL,
col_int_key int(11) DEFAULT NULL,
pk int(11) NOT NULL AUTO_INCREMENT,
col_varchar_10_latin1 varchar(10) DEFAULT NULL,
PRIMARY KEY (pk)
);
INSERT INTO t1 VALUES (5,5,1,'t'), (NULL,NULL,2,'y');
CREATE TABLE t2 (
col_int int(11) DEFAULT NULL
);
INSERT INTO t2 VALUES (8), (4);
CREATE TABLE t3 (
pk int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (pk)
);
INSERT INTO t3 VALUES (1),(8);
CREATE TABLE t4 (
pk int(11) NOT NULL AUTO_INCREMENT,
col_varchar_1024_latin1_key varchar(1024) DEFAULT NULL,
col_int int(11) DEFAULT NULL,
PRIMARY KEY (pk)
);
INSERT INTO t4 VALUES (1,'o',1), (2,'w',2);
CREATE TABLE t5 (
col_varchar_1024_utf8_key varchar(1024) CHARACTER SET utf8 DEFAULT NULL,
col_varchar_1024_latin1_key varchar(1024) DEFAULT NULL,
col_varchar_10_utf8_key varchar(1024) CHARACTER SET utf8 DEFAULT NULL,
pk int(11) NOT NULL AUTO_INCREMENT,
col_int_key int(11) DEFAULT NULL,
PRIMARY KEY (pk)
);
INSERT INTO t5 VALUES ('k','a','z',1,2),('x','a','w',2,7);
CREATE TABLE t6 (
col_int int(11) DEFAULT NULL,
col_int_key int(11) DEFAULT NULL
);
INSERT INTO t6 VALUES (6,1),(8,3);
SELECT
table3.col_int AS field1,
table1.col_int AS field2,
table1.col_int_key AS field3,
table1.pk AS field4,
table1.col_int AS field5,
table2.col_int AS field6
FROM
t1 AS table1
LEFT OUTER JOIN
t4 AS table2
LEFT JOIN t6 AS table3
RIGHT JOIN t3 AS table4
LEFT JOIN t5 AS table5 ON table4.pk = table5.pk
LEFT JOIN t0 AS table6 ON table5.col_int_key = table6.pk
ON table3.col_int_key = table5.pk
ON table2.col_varchar_1024_latin1_key = table5.col_varchar_10_utf8_key
LEFT JOIN t6 AS table7 ON table2.pk = table7.col_int
ON table1.col_varchar_10_latin1 = table5.col_varchar_1024_latin1_key
LEFT JOIN t2 AS table8 ON table3.col_int = table8.col_int
WHERE
table1.col_int_key < table2.pk
HAVING
field4 != 6;
field1	field2	field3	field4	field5	field6
drop table t0,t1,t2,t3,t4,t5,t6;
#
# BUG#675118: Elimination of a table results in an invalid execution plan
#
CREATE TABLE t1 (f1 int(11), PRIMARY KEY (f1)) ;
CREATE TABLE t2 (f4 varchar(1024), KEY (f4)) ;
Warnings:
Note	1071	Specified key was too long; max key length is 1000 bytes
INSERT IGNORE INTO t2 VALUES ('xcddwntkbxyorzdv'),
('cnxxcddwntkbxyor'),('r'),('r'), ('did'),('I'),('when'),
('hczkfqjeggivdvac'),('e'),('okay'),('up');
CREATE TABLE t3 (f4 varchar(1024), f1 int(11), f2 int(11)) ;
INSERT IGNORE INTO t3 VALUES ('f','4','0'),('n','5','-996540416');
CREATE TABLE t4 (f1 int(11), f3 varchar(10)) ;
INSERT IGNORE INTO t4 VALUES ('8','n'),('9','nwzcerzsgx'),('10','c');
CREATE TABLE t5 (f5 int(11), KEY (f5)) ;
EXPLAIN 
SELECT t3.f2
FROM t2
LEFT JOIN t3
LEFT JOIN t4
LEFT JOIN t1 ON t4.f1 = t1.f1
JOIN t5 ON t4.f3 ON t3.f1 = t5.f5 ON t2.f4 = t3.f4
WHERE t3.f2 ;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	2	Using where
1	SIMPLE	t5	ref	f5	f5	5	test.t3.f1	2	Using where; Using index
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	3	Using where
1	SIMPLE	t2	ALL	f4	NULL	NULL	NULL	11	Using where; Using join buffer (flat, BNL join)
# ^^ The above must not produce a QEP of t3,t5,t2,t4
#    as that violates the "no interleaving of outer join nests" rule.
DROP TABLE t1,t2,t3,t4,t5;
#
# BUG#997747: Assertion `join->best_read < ((double)1.79..5e+308L)' 
#             failed in greedy_search with LEFT JOINs and unique keys  
#
CREATE TABLE t1 (a1 INT);
CREATE TABLE t2 (b1 INT);
CREATE TABLE t3 (c1 INT, UNIQUE KEY(c1));
CREATE TABLE t4 (d1 INT, UNIQUE KEY(d1));
CREATE TABLE t5 (e1 INT);
INSERT INTO t1 VALUES (1),(2);
INSERT INTO t2 VALUES (2),(3);
INSERT INTO t3 VALUES (3),(4);
INSERT INTO t4 VALUES (4),(5);
INSERT INTO t5 VALUES (5),(6);
SELECT a1 FROM t1 LEFT JOIN t2 LEFT JOIN t3 LEFT JOIN t4
ON c1 = d1 ON d1 = b1 ON a1 = b1
LEFT JOIN t5 ON a1 = e1 ;
a1
1
2
DROP TABLE t1,t2,t3,t4,t5;
#
# BUG#884184: Wrong result with RIGHT JOIN + derived_merge
#
CREATE TABLE t1 (a int(11), b varchar(1)) ;
INSERT IGNORE INTO t1 VALUES (0,'g');
CREATE TABLE t3 ( a varchar(1)) ;
INSERT IGNORE INTO t3 VALUES ('g');
CREATE TABLE t2 ( a int(11) NOT NULL, PRIMARY KEY (a));
INSERT INTO t2 VALUES (9), (10);
create view v1 as SELECT t1.* FROM t1 LEFT JOIN t2 ON ( t1.a = t2.a ) WHERE t2.a <> 0;
SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
a	b
NULL	NULL
EXPLAIN SELECT alias1.* FROM t3 LEFT JOIN v1 as alias1 ON ( t3.a = alias1.b );
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	system	NULL	NULL	NULL	NULL	1	
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	1	Using where
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
drop view v1;
DROP TABLE t1,t2,t3;
#
# MDEV-5344: LEFT OUTER JOIN table data is lost in ON DUPLICATE KEY UPDATE section
#
create table t1 (
id int(10) unsigned NOT NULL DEFAULT '0',
v int(10) unsigned DEFAULT '0',
PRIMARY KEY (id)
);
create table t2 (
id int(10) unsigned NOT NULL DEFAULT '0',
PRIMARY KEY (id)
) ;
create table t3 (
id int(10) unsigned NOT NULL DEFAULT '0',
v int(10) unsigned DEFAULT '0',
PRIMARY KEY (id)
);
insert into t1 values (1, 10), (2, 10);
insert into t2 values (1), (2);
insert into t3 values (1, 20);
insert into t1 
select t2.id, 5 from t2 LEFT OUTER JOIN t3 ON t2.id = t3.id
on duplicate key update t1.v = t3.v;
select * from t1;
id	v
1	20
2	NULL
drop table t1,t2,t3;
#
# BUG#919878: Assertion `!eliminated_tables...
#
CREATE TABLE t1 ( a INT );
INSERT INTO t1 VALUES (1);
CREATE TABLE t2
( b INT, UNIQUE INDEX(b) );
INSERT INTO t2 VALUES (1),(2);
EXPLAIN EXTENDED
SELECT * FROM t2
WHERE b IN (
SELECT SUM(a) FROM t1 LEFT JOIN t2 ON b=a
);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	t2	index	NULL	b	5	NULL	2	100.00	Using where; Using index
2	DEPENDENT SUBQUERY	t1	system	NULL	NULL	NULL	NULL	1	100.00	
Warnings:
Note	1003	/* select#1 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` where <expr_cache><`test`.`t2`.`b`>(<in_optimizer>(`test`.`t2`.`b`,<exists>(/* select#2 */ select sum(1) from dual where 1 having <cache>(`test`.`t2`.`b`) = <ref_null_helper>(sum(1)))))
DROP TABLE t1,t2;
#
# MDEV-4840: Wrong result (missing rows) on LEFT JOIN with InnoDB tables
#
CREATE TABLE t1 (alpha3 VARCHAR(3));
INSERT INTO t1 VALUES ('USA'),('CAN');
CREATE TABLE t2 ( t3_code VARCHAR(3), name VARCHAR(64));
INSERT INTO t2 VALUES ('USA','Austin'),('USA','Boston');
CREATE TABLE t3 ( code VARCHAR(3),  name VARCHAR(64),  PRIMARY KEY (code),  UNIQUE KEY (name));
INSERT INTO t3 VALUES ('CAN','Canada'),('USA','United States');
SELECT *         FROM t1 LEFT JOIN ( t2 LEFT JOIN t3 ON t2.t3_code  = t3.code ) ON t1.alpha3 = t3.code;
alpha3	t3_code	name	code	name
USA	USA	Austin	USA	United States
USA	USA	Boston	USA	United States
CAN	NULL	NULL	NULL	NULL
SELECT t1.alpha3 FROM t1 LEFT JOIN ( t2 LEFT JOIN t3 ON t2.t3_code  = t3.code ) ON t1.alpha3 = t3.code;
alpha3
USA
USA
CAN
DROP TABLE t1, t2, t3;
SET optimizer_switch=@save_optimizer_switch;
#
# MDEV-7893: table_elimination works wrong with on computed expression and compound unique key
#  (just a testcase)
CREATE TABLE t1 (
PostID int(10) unsigned NOT NULL
) DEFAULT CHARSET=utf8;
INSERT INTO t1 (PostID) VALUES (1), (2);
CREATE TABLE t2 (
VoteID int(10) unsigned NOT NULL PRIMARY KEY AUTO_INCREMENT,
EntityID int(10) unsigned NOT NULL,
UserID int(10) unsigned NOT NULL,
UNIQUE KEY EntityID (EntityID,UserID)
) DEFAULT CHARSET=utf8;
INSERT INTO t2 (EntityID, UserID) VALUES (1,  30), (2, 30);
SELECT t1.*, T.Voted as Voted
FROM 
t1 LEFT JOIN (
SELECT 1 AS Voted, EntityID 
FROM t2 
WHERE t2.UserID = '20' ) AS T 
ON T.EntityID = t1.PostID
WHERE t1.PostID='1'
LIMIT 1;
PostID	Voted
1	NULL
DROP TABLE t1,t2;
#
# MDEV-26278: Table elimination does not work across derived tables
#
create table t1 (a int, b int);
insert into t1 select seq, seq+10 from seq_1_to_10;
create table t11 (
a int not null,
b int,
key(a)
);
insert into t11 select A.seq, A.seq+B.seq
from
seq_1_to_10 A,
seq_1_to_100 B;
create table t12 (
pk int primary key,
col1 int
);
insert into t12 select seq, seq from seq_1_to_1000;
create view v2b as 
select t11.a as a, count(*) as b
from t11 left join t12 on t12.pk=t11.b
group by t11.a;
# The whole v2b is eliminated
explain select t1.* from t1 left join v2b on v2b.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
# Check format JSON as well
explain format=JSON select t1.* from t1 left join v2b on t1.a=v2b.a;
EXPLAIN
{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "nested_loop": [
      {
        "table": {
          "table_name": "t1",
          "access_type": "ALL",
          "rows": 10,
          "filtered": 100
        }
      }
    ]
  }
}
# Elimination of a whole subquery 
explain select t1.* from t1 left join 
(select t11.a as a, count(*) as b
from t11 left join t12 on t12.pk=t11.b
group by t11.a) v2b on v2b.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
# In this case v2b cannot be eliminated (since v2b.b is not unique)!
explain select t1.* from t1 left join v2b on t1.a=v2b.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
1	PRIMARY	<derived2>	ref	key0	key0	8	test.t1.a	10	Using where
2	DERIVED	t11	ALL	NULL	NULL	NULL	NULL	1000	Using temporary; Using filesort
# Check format JSON as well
explain format=JSON select t1.* from t1 left join v2b on t1.a=v2b.b;
EXPLAIN
{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "nested_loop": [
      {
        "table": {
          "table_name": "t1",
          "access_type": "ALL",
          "rows": 10,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "<derived2>",
          "access_type": "ref",
          "possible_keys": ["key0"],
          "key": "key0",
          "key_length": "8",
          "used_key_parts": ["b"],
          "ref": ["test.t1.a"],
          "rows": 10,
          "filtered": 100,
          "attached_condition": "trigcond(t1.a = v2b.b and trigcond(t1.a is not null))",
          "materialized": {
            "query_block": {
              "select_id": 2,
              "const_condition": "1",
              "filesort": {
                "sort_key": "t11.a",
                "temporary_table": {
                  "nested_loop": [
                    {
                      "table": {
                        "table_name": "t11",
                        "access_type": "ALL",
                        "rows": 1000,
                        "filtered": 100
                      }
                    }
                  ]
                }
              }
            }
          }
        }
      }
    ]
  }
}
create view v2c as 
select t11.a as a, max(t12.col1) as b
from t11 left join t12 on t12.pk=t11.b
group by t11.a;
# The whole v2c is eliminated
explain select t1.* from t1 left join v2c on v2c.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
# Check format JSON as well
explain format=JSON select t1.* from t1 left join v2c on v2c.a=t1.a;
EXPLAIN
{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "nested_loop": [
      {
        "table": {
          "table_name": "t1",
          "access_type": "ALL",
          "rows": 10,
          "filtered": 100
        }
      }
    ]
  }
}
# In this case v2c cannot be eliminated (since v2c.b is not unique)!
explain select t1.* from t1 left join v2c on t1.a=v2c.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
1	PRIMARY	<derived2>	ref	key0	key0	5	test.t1.a	10	Using where
2	DERIVED	t11	ALL	NULL	NULL	NULL	NULL	1000	Using temporary; Using filesort
2	DERIVED	t12	eq_ref	PRIMARY	PRIMARY	4	test.t11.b	1	Using where
# Check format JSON as well
explain format=JSON select t1.* from t1 left join v2c on t1.a=v2c.b;
EXPLAIN
{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "nested_loop": [
      {
        "table": {
          "table_name": "t1",
          "access_type": "ALL",
          "rows": 10,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "<derived2>",
          "access_type": "ref",
          "possible_keys": ["key0"],
          "key": "key0",
          "key_length": "5",
          "used_key_parts": ["b"],
          "ref": ["test.t1.a"],
          "rows": 10,
          "filtered": 100,
          "attached_condition": "trigcond(trigcond(t1.a is not null))",
          "materialized": {
            "query_block": {
              "select_id": 2,
              "const_condition": "1",
              "filesort": {
                "sort_key": "t11.a",
                "temporary_table": {
                  "nested_loop": [
                    {
                      "table": {
                        "table_name": "t11",
                        "access_type": "ALL",
                        "rows": 1000,
                        "filtered": 100
                      }
                    },
                    {
                      "table": {
                        "table_name": "t12",
                        "access_type": "eq_ref",
                        "possible_keys": ["PRIMARY"],
                        "key": "PRIMARY",
                        "key_length": "4",
                        "used_key_parts": ["pk"],
                        "ref": ["test.t11.b"],
                        "rows": 1,
                        "filtered": 100,
                        "attached_condition": "trigcond(trigcond(t11.b is not null))"
                      }
                    }
                  ]
                }
              }
            }
          }
        }
      }
    ]
  }
}
# Create a view with multiple fields in the GROUP BY clause:
create view v2d as 
select t11.a as a, t11.b as b, max(t12.col1) as max_col1
from t11 left join t12 on t12.pk=t11.b
group by t11.a, t11.b;
# This one must not be eliminated since only one of the GROUP BY fields is bound:
explain select t1.* from t1 left join v2d on v2d.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
1	PRIMARY	<derived2>	ref	key0	key0	5	test.t1.a	10	Using where
2	DERIVED	t11	ALL	a	NULL	NULL	NULL	1000	Using temporary; Using filesort
2	DERIVED	t12	eq_ref	PRIMARY	PRIMARY	4	test.t11.b	1	Using where
# This must be eliminated since both fields are bound:
explain select t1.* from t1 left join v2d on v2d.a=t1.a and v2d.b=t1.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
create table t13 (dt date, b int);
# Function year() in the GROUP BY list prevents treating this field 
# as a unique key
create view v2e as
select year(t13.dt) as yyy, max(t12.col1) as max_col1
from t13 join t12 on t12.pk=t13.b
group by yyy;
# No elimination here since function year() is used
explain select t1.* from t1 left join v2e on v2e.yyy=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
1	PRIMARY	<derived2>	ref	key0	key0	5	test.t1.a	2	Using where
2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	no matching row in const table
create table t2 (a int, b int, c int);
insert into t2 select A.seq, B.seq, 123 from seq_1_to_3 A, seq_1_to_3 B;
# No elimination here since not all fields of the derived table's 
# GROUP BY are on the SELECT list so D.a is not unique
explain select t1.* from t1 left join 
(select a, count(*) as cnt from t2 group by a, b) D on D.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
1	PRIMARY	<derived2>	ref	key0	key0	5	test.t1.a	2	Using where
2	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
# Still no elimination 'cause field D.b is just an alias for t2.a
explain select t1.* from t1 left join 
(select a, a as b, count(*) as cnt from t2 group by a, b) D on D.a=t1.a and D.b=t1.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
1	PRIMARY	<derived2>	ref	key0	key0	10	test.t1.a,test.t1.b	2	Using where
2	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
Warnings:
Warning	1052	Column 'b' in GROUP BY is ambiguous
# Now both a and b fields are on the SELECT list and they are bound to t1
# so derived D must be eliminated
explain select t1.* from t1 left join 
(select a as a1, b as b1, count(*) as cnt from t2 group by a, b) D 
on D.a1=t1.a and D.b1=t1.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
# Different order of fields in GROUP BY and SELECT lists
# must not hamper the elimination
explain select t1.* from t1 left join 
(select count(*) as cnt, b, a from t2 group by a, b) D on D.a=t1.a and D.b=t1.b;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	10	
drop view v2b, v2c, v2d, v2e;
drop table t1, t11, t12, t13, t2;
#
# End of MDEV-26278: Table elimination does not work across derived tables
#
#
# MDEV-28881: Server crashes in Dep_analysis_context::create_table_value/
#                                check_func_dependency
#
CREATE TABLE t1 (a1 int, a2 int);
INSERT INTO t1 VALUES (0,276),(5,277),(NULL,278);
CREATE TABLE t2 ( a1 int, a2 int, KEY a2 (a2));
INSERT INTO t2 VALUES (11,NULL),(185,0);
SELECT t1.* FROM t1 LEFT JOIN
( SELECT * FROM (SELECT t2.a1 AS a1, min(t2.a2) AS a2 FROM t2
WHERE t2.a2 <> NULL
GROUP BY t2.a1) dt
) dt2 ON dt2.a2 = t1.a2;
a1	a2
0	276
5	277
NULL	278
DROP TABLE t1, t2;
#
# MDEV-30007: SIGSEGV in st_select_lex_unit::is_derived_eliminated,
# runtime error: member access within null pointer of type
# 'struct TABLE' in st_select_lex_unit::is_derived_eliminated()
#
CREATE VIEW v AS SELECT 1 AS a;
SELECT ROUND ((SELECT 1 FROM v)) FROM v GROUP BY ROUND ((SELECT 1 FROM v));
ROUND ((SELECT 1 FROM v))
1
EXPLAIN
SELECT ROUND ((SELECT 1 FROM v)) FROM v GROUP BY ROUND ((SELECT 1 FROM v));
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	<derived4>	system	NULL	NULL	NULL	NULL	1	
4	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
2	SUBQUERY	<derived5>	system	NULL	NULL	NULL	NULL	1	
5	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
DROP VIEW v;
#
# End of 10.10 tests
#
#
# MDEV-36215: Table elimination wrongly done
#
CREATE TABLE t1(null_col INT, notnull_col INT NOT NULL);
CREATE TABLE t2(unique_col INT, UNIQUE(unique_col));
INSERT INTO t1 VALUES (1,100), (NULL, 101);
INSERT INTO t2 VALUES (NULL), (NULL);
# Test with 'unique_col IS NULL'
# Here, table t2 should not be eliminated:
explain
select t1.null_col from t1 left join t2 on (t2.unique_col is null);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
1	SIMPLE	t2	ref	unique_col	unique_col	5	const	2	Using where; Using index
select t1.null_col from t1 left join t2 on (t2.unique_col is null);
null_col
1
1
NULL
NULL
# Check without table elimination:
set statement optimizer_switch='table_elimination=off' for
select t1.null_col from t1 left join t2 on (t2.unique_col is null);
null_col
1
1
NULL
NULL
# Test with 'unique_col <=> nullable_col'
# t2 must not be eliminated:
explain
select t1.null_col from t1 left join t2 on t1.null_col<=>t2.unique_col;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
1	SIMPLE	t2	ref	unique_col	unique_col	5	test.t1.null_col	2	Using where; Using index
select t1.null_col from t1 left join t2 on t1.null_col<=>t2.unique_col;
null_col
1
NULL
NULL
# Check without table elimination:
set statement optimizer_switch='table_elimination=off' for
select t1.null_col from t1 left join t2 on t1.null_col<=>t2.unique_col;
null_col
1
NULL
NULL
# Table t2 will be eliminated:
explain
select t1.null_col from t1 left join t2 on (t2.unique_col<=>t1.notnull_col);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
DROP TABLE t1, t2;
#
# End of 10.11 tests
#