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mysql> explain SELECT * FROM `bw_thread` WHERE thread_parent = 'X';
+----+-------------+-----------+------+---------------+------+---------+------+-------+-------------+
| id | select_type | table     | type | possible_keys | key  | key_len | ref  | rows  | Extra       |
+----+-------------+-----------+------+---------------+------+---------+------+-------+-------------+
|  1 | SIMPLE      | bw_thread | ALL  | NULL          | NULL | NULL    | NULL | 27835 | Using where |
+----+-------------+-----------+------+---------------+------+---------+------+-------+-------------+

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