mariadb/mysql-test/t/subselect3.test

--disable_warnings
drop table if exists t0, t1, t2, t3, t4;
--enable_warnings

#
# 1. Subquery with GROUP/HAVING
#
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);

#  Ok, for  
#   select max(ie) from t1 where oref=PARAM group by grp
# we'll have:
#  1  ->  (1, NULL)    matching + NULL
#  2  ->  (3)          non-matching
#  3  ->  (3, NULL)    non-matching + NULL
#  4  ->  ()           nothing.

create table t2 (oref int, a int);
insert into t2 values 
  (1, 1),
  (2, 2),
  (3, 3),
  (4, NULL),
  (2, NULL);

# true, false, null, false, null
select a, oref, a in (select max(ie) 
  from t1 where oref=t2.oref group by grp) from t2;

# This must have a trigcond
explain extended
select a, oref, a in (select max(ie) 
  from t1 where oref=t2.oref group by grp) from t2;

# This must not have a trigcond:
explain extended
select a, oref from t2 
where a in (select max(ie) from t1 where oref=t2.oref group by grp);


# Non-correlated subquery, 2 NULL evaluations
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;
show status like 'Handler_read_rnd_next';
select ' ^ This must show 11' Z;

# This must show trigcond:
explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;

drop table t1, t2, t3;

# 
#  2. Subquery handled with 'index_subquery':
# 
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;

# The next explain shows "using index" but that is just incorrect display
# (there is a bug filed about this).
explain extended 
select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;

flush status;
select oref, a from t2 where a in (select a from t1 where oref=t2.oref);
# This will only show access to t2:
show status like '%Handler_read_rnd_next';

# Check that repeated NULL-scans are not cached (subq. is not correlated):
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;
show status like '%Handler_read%';
select 'No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.' Z;

drop table t1, t2;

#
# 3. Subquery handled with 'unique_index_subquery':
#
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 ;

drop table t1, t2;

#
# 4. Subquery that is a join, with ref access
#
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;

# This must have trigcond in WHERE and HAVING:
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;

drop table t1, t2, t3;