Shows combined primary keys on innodb

primary_keys.sql

create table bla(
    b int, 
    id int not null auto_increment, 
    primary key (b, id), 
    unique key (id)
) engine=innodb;

insert into bla (b) values (1), (2), (1), (2);

/* this looks like "order by id, b" because with small tables mysql doesn't use the primary key */
select * from bla;

/*
+---+----+
| b | id |
+---+----+
| 1 |  1 |
| 2 |  2 |
| 1 |  3 |
| 2 |  4 |
+---+----+
*/


/* force primary to see insertion/on disk order */
select * from bla force index (PRIMARY);

/*
+---+----+
| b | id |
+---+----+
| 1 |  1 |
| 1 |  3 |
| 2 |  2 |
| 2 |  4 |
+---+----+
*/