MySQL [test]> create table t1 (c char(1), i int, primary key(c), key(i)) engine=LevelDB;

Query OK, 0 rows affected (0.15 sec)

MySQL [test]> insert into t1 values ('2',2),('6',6);

Query OK, 2 rows affected (0.01 sec)

Records: 2  Duplicates: 0  Warnings: 0

MySQL [test]> explain extended

    -> select * from t1 where c = i;

+----+-------------+-------+-------+---------------+------+---------+------+------+----------+--------------------------+

| id | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | filtered | Extra                    |

+----+-------------+-------+-------+---------------+------+---------+------+------+----------+--------------------------+

|  1 | SIMPLE      | t1    | index | NULL          | i    | 5       | NULL | 1000 |   100.00 | Using where; Using index |

+----+-------------+-------+-------+---------------+------+---------+------+------+----------+--------------------------+

1 row in set, 1 warning (0.00 sec)

MySQL [test]> 

MySQL [test]> select * from t1 where c = i;

+---+------+

| c | i    |

+---+------+

| 6 |    6 |

+---+------+

1 row in set (0.00 sec)

drop table if exists t1;

create table t1 (c char(1), i int, primary key(c), key(i)) engine=LevelDB;

insert into t1 values ('2',2),('6',6);

select * from t1 where c = i;

revision-id: psergey@askmonty.org-20130327131855-qxesm69dxnr3kcgy

revno: 4818

branch-nick: mysql-5.6-leveldb