1. mysql> explain SELECT id
  2. -> FROM file
  3. -> WHERE size IN
  4. -> ( SELECT size FROM tmpTab );
  5. +----+--------------------+--------+-------+---------------+----------+---------
  6. +------+-------+--------------------------+
  7. | id | select_type | table | type | possible_keys | key | key_len
  8. | ref | rows | Extra |
  9. +----+--------------------+--------+-------+---------------+----------+---------
  10. +------+-------+--------------------------+
  11. | 1 | PRIMARY | file | index | NULL | filesize | 8
  12. | NULL | 21168 | Using where; Using index |
  13. | 2 | DEPENDENT SUBQUERY | tmpTab | ALL | NULL | NULL | NULL
  14. | NULL | 3197 | Using where |
  15. +----+--------------------+--------+-------+---------------+----------+---------
  16. +------+-------+--------------------------+
  17. 2 rows in set (0.00 sec)