use mysql;

--disable_warnings
drop table if exists t1, t1_part1, t1_part2;
--enable_warnings
create table t1_part1
(
  a int primary key,
  b varchar(30)
) ENGINE = MYISAM ;
create table t1_part2
(
  a int primary key,
  b varchar(30)
) ENGINE = MYISAM ;
create table t1
(
  a int primary key,
  b varchar(30),
  index(a)
) ENGINE = MERGE UNION=(t1_part1,t1_part2)
INSERT_METHOD=LAST;
commit ;


insert into t1 values(6, 'six' );
# the second insert fails, because the first column is primary key
--error 1022
insert into t1 values(6, NULL );
select a,b from t1 ;

Select "###### the insert should not fail !!! #####" as my_col ;
Select "please remove the '--error 1022' line" as my_col ;
--error 1022
insert into t1 set a=6, b='sechs'
on duplicate key update a=a + 1, b='modified' ;
select a,b from t1 ;