Suppose you have the following table and data:

    create table t (
        k int,
        v int,
        index k(k)
        ) engine=memory;

    insert into t (k, v)
    values (10, 1),
           (10, 2),
           (10, 3);

When issuing `select * from t where k = 10` with no `order by` clause, how does MySQL sort the records by default?