drop database if exists test1;
create database test1;use test1;
create table t1 (a int);
insert into t1 select seq from seq_1_to_10000;

create table t2 (
  a int,
  b int,
  index(a)
);
insert into t2
select
  A.seq,
  B.seq
from
  seq_1_to_1000 A,
  seq_1_to_10 B;

create table t3 (
  a int,
  b int,
  index(a)
);
insert into t3
select
  A.seq,
  A.seq
from
  seq_1_to_1000 A;
drop index a on t2;
drop index a on t3;
