65
65
alter table t1 drop primary key, add primary key (f2, f1);
66
66
explain select distinct f1 a, f1 b from t1;
67
67
id select_type table type possible_keys key key_len ref rows Extra
69
69
explain select distinct f1, f2 from t1;
70
70
id select_type table type possible_keys key key_len ref rows Extra