優化SQL查詢在MySQL數據庫

Question

我有以下查詢：

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 

我試圖通過增加對（r.from，r.to）的指數，以優化這個查詢，但我並沒有奏效。

當我讓我解釋一下這個查詢它說：

+----+-------------+-------+--------+---------------+---------+---------+-------------+------+-----------------------------+ 
| 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) 

爲什麼呢？

謝謝你的幫助。

Answer 1

複合指數不會幫助你，因爲你有不同的比較功能的條件。嘗試在r.from和r.to上添加單獨的索引。實際上，我認爲r.from上的一個索引就足夠了。