diff.sql

create table example (id_1 integer, id_2 integer);

-- Insert lots of equal id_1
insert into example (id_1, id_2) values (1, 1);
insert into example (id_1, id_2) values (0, 3);
insert into example (id_1, id_2) values (0, 2);
insert into example (id_1, id_2) values (0, 3);
insert into example (id_1, id_2) values (0, 2);
insert into example (id_1, id_2) values (0, 3);
insert into example (id_1, id_2) values (1, 3);

-- Order only by the first element, second
-- is undefined for equal first elements.
select * from example order by id_1;