create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

create table t1 (a int, b int);

insert into t1 select 1, A.a *10000 + B.a * 1000 + C.a * 100 + D.a * 10
from t0 A, t0 B, t0 C, t0 D, t0 E;

select max(a*b) from t1 where a > b;
--disable_query_log

let $1= 10;
begin;
while ($1)
{
  alter table t1 add key(a);
  select max(a*b) from t1 where a > b;
  alter table t1 drop key a;
  dec $1;
}

--enable_query_log
drop table t0, t1;