优化SQL查询在MySQL数据库

Question

我有以下查询：

SELECT * , r.id, x.real_name AS u_real_name, u.real_name AS v_real_name, y.real_name AS v_real_name2 
FROM url_urlaube r 
LEFT JOIN g_users u ON (r.v_id = u.id) 
LEFT JOIN g_users x ON (r.u_id = x.id) 
LEFT JOIN g_users y ON (r.v_id2 = y.id) 
WHERE (
(
FROM_UNIXTIME(1283205600) >= r.from 
AND FROM_UNIXTIME(1283205600) <= r.to 
) 
OR (
FROM_UNIXTIME(1280613600) >= r.from 
AND FROM_UNIXTIME(1280613600) <= r.to 
) 
OR (
FROM_UNIXTIME(1280613600) < r.from 
AND FROM_UNIXTIME(1283205600) > r.to 
) 
) 
ORDER BY r.from ASC 

我试图通过增加对（r.from，r.to）的指数，以优化这个查询，但我并没有奏效。

当我让我解释一下这个查询它说：

+----+-------------+-------+--------+---------------+---------+---------+-------------+------+-----------------------------+ 
| id | select_type | table | type | possible_keys | key  | key_len | ref   | rows | Extra      | 
+----+-------------+-------+--------+---------------+---------+---------+-------------+------+-----------------------------+ 
| 1 | SIMPLE  | r  | ALL | from   | NULL | NULL | NULL  | 42 | Using where; Using filesort | 
| 1 | SIMPLE  | u  | eq_ref | PRIMARY  | PRIMARY | 4  | res.r.v_id | 1 |        | 
| 1 | SIMPLE  | x  | eq_ref | PRIMARY  | PRIMARY | 4  | res.r.u_id | 1 |        | 
| 1 | SIMPLE  | y  | eq_ref | PRIMARY  | PRIMARY | 4  | res.r.v_id2 | 1 |        | 
+----+-------------+-------+--------+---------------+---------+---------+-------------+------+-----------------------------+ 
4 rows in set (0.00 sec) 

为什么呢？

谢谢你的帮助。

Answer 1

复合指数不会帮助你，因为你有不同的比较功能的条件。尝试在r.from和r.to上添加单独的索引。实际上，我认为r.from上的一个索引就足够了。