SET DEFAULT_STORAGE_ENGINE = 'tokudb'; DROP TABLE IF EXISTS foo; create table foo (a int, b int, c int, primary key (a), clustering key (b)); replace into foo values (1,10,100), (2,20,200), (1,10,1000); explain select * from foo; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE foo ALL NULL NULL NULL NULL 2 select * from foo; a b c 1 10 1000 2 20 200 explain select * from foo order by b desc; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE foo index NULL b 5 NULL 2 select * from foo order by b desc; a b c 2 20 200 1 10 1000 insert ignore into foo values (3,30,300), (1,10,1); explain select * from foo; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE foo ALL NULL NULL NULL NULL 3 select * from foo; a b c 1 10 1000 2 20 200 3 30 300 explain select * from foo order by b desc; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE foo index NULL b 5 NULL 3 select * from foo order by b desc; a b c 3 30 300 2 20 200 1 10 1000 drop table foo;