Forum libero

> SELECT last_global.threadid
> FROM 
> (SELECT threadid, max(id) AS mid FROM messages 
> GROUP BY threadid ORDER BY mid DESC LIMIT 512) 
> AS last_global, 
> (SELECT threadid FROM messages 
> WHERE author = 'Giambo'
> GROUP BY threadid ORDER BY max(id) DESC LIMIT 512) 
> AS last_author 
> WHERE last_author.threadid = last_global.threadid 
> ORDER BY last_global.mid
> 

+----------+----------+------+-----+---------+----------------+
| Field    | Type     | Null | Key | Default | Extra          |
+----------+----------+------+-----+---------+----------------+
| id       | int(11)  | NO   | PRI | NULL    | auto_increment |
| text     | longtext | NO   | MUL | NULL    |                |
| date     | datetime | NO   |     | NULL    |                |
| subject  | tinytext | NO   |     | NULL    |                |
| threadId | int(11)  | NO   | MUL | NULL    |                |
| parentId | int(11)  | NO   | MUL | NULL    |                |
| author   | tinytext | YES  |     | NULL    |                |
| forum    | tinytext | YES  |     | NULL    |                |
+----------+----------+------+-----+---------+----------------+

+----+-------------+------------+------+---------------+------+---------+------+--------+---------------------------------+
| id | select_type | table      | type | possible_keys | key  | key_len | ref  | rows   | Extra                           |
+----+-------------+------------+------+---------------+------+---------+------+--------+---------------------------------+
|  1 | PRIMARY     | <derived2> | ALL  | NULL          | NULL | NULL    | NULL |    512 | Using temporary; Using filesort |
|  1 | PRIMARY     | <derived3> | ALL  | NULL          | NULL | NULL    | NULL |    512 | Using where; Using join buffer  |
|  3 | DERIVED     | messages   | ALL  | NULL          | NULL | NULL    | NULL | 928694 | Using temporary; Using filesort |
|  2 | DERIVED     | messages   | ALL  | NULL          | NULL | NULL    | NULL | 928694 | Using temporary; Using filesort |
+----+-------------+------------+------+---------------+------+---------+------+--------+---------------------------------+