mysql> explain  SELECT ac,rc,t.debtor_no,coll_unit FROM transactionTbl t,masterTbl m WHERE t.debtor_no = m.debtor_no order by debtor_no limit         10;

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

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

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

|  1 | SIMPLE      | m     | ALL  | masterMasterNoIdx         | NULL            |    NULL | NULL                | 2582527 | Using temporary; Using filsort |

|  1 | SIMPLE      | t     | ref  | tranMasterNoIdx,debtor_no | tranMasterNoIdx |       7 | crsdata.m.debtor_no |      37 | Using where                    |

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

2 rows in set (4 min 49.60 sec)