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

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

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

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

|  1 | SIMPLE      | t     | ALL  | tranMasterNoIdx,debtor_no   | NULL      |    NULL | NULL                | 56922472 |             |

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

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

2 rows in set (0.03 sec)