rendered paste bodymysql> 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)