gistfile1.txt

> explain select * FROM   dna INNER JOIN   seq_region USING   (seq_region_id) WHERE   coord_system_id = 3;
+----+-------------+------------+--------+----------------+---------+---------+-------------------------------------------
----------+------+-------+
| id | select_type | table      | type   | possible_keys  | key     | key_len | ref                                       
          | rows | Extra |
+----+-------------+------------+--------+----------------+---------+---------+-------------------------------------------
----------+------+-------+
|  1 | SIMPLE      | seq_region | ref    | PRIMARY,cs_idx | cs_idx  | 4       | const                                     
          | 2174 |       |
|  1 | SIMPLE      | dna        | eq_ref | PRIMARY        | PRIMARY | 4       | brassica_rapa_core_13_66_1.seq_region.seq_region_id |    1 |       |
+----+-------------+------------+--------+----------------+---------+---------+-----------------------------------------------------+------+-------+
2 rows in set (0.00 sec)