mysql在時間跨度查詢優化之間進行選擇

Question

就這樣，根據我最後一個問題here我之一finnaly想出了這個查詢，基本上拉的任何用戶，在任何24小時的時間內超過100次下載。

SELECT *, 
     users.userid AS IP, 
     MAX(ucount) 
    FROM (SELECT t1.user_id, 
       t1.data DE, 
       ADDTIME(t1.data,'24:00:00') A, 
       (SELECT COUNT(1) 
        FROM downloads t2 
       WHERE t1.user_id = t2.user_id 
        AND t1.data <= t2.data 
        AND ADDTIME(t1.data,'24:00:00') >= t2.data) ucount 
      FROM downloads t1) t3 
LEFT JOIN users ON users.id = t3.user_id 
    WHERE ucount > 100 
GROUP BY IP 

的是，具有〜40K記錄和用戶表〜9K區域經濟共同體，這是我所得到的性能明智的下載表格：

8 rows in set (9.18 sec) 

對於這個問題的，解釋來liek這

+----+--------------------+------------+--------+---------------+---------+---------+-----------------------+-------+----------------------------------------------+ 
| id | select_type  | table  | type | possible_keys | key  | key_len | ref     | rows | Extra          | 
+----+--------------------+------------+--------+---------------+---------+---------+-----------------------+-------+----------------------------------------------+ 
| 1 | PRIMARY   | <derived2> | ALL | NULL   | NULL | NULL | NULL     | 38949 | Using where; Using temporary; Using filesort | 
| 1 | PRIMARY   | users  | eq_ref | PRIMARY  | PRIMARY | 4  | t3.user_id   |  1 |            | 
| 2 | DERIVED   | t1   | ALL | NULL   | NULL | NULL | NULL     | 38949 |            | 
| 3 | DEPENDENT SUBQUERY | t2   | ref | users,data | users | 4  | admin_beta.t1.user_id |  5 | Using where         | 
+----+--------------------+------------+--------+---------------+---------+---------+-----------------------+-------+----------------------------------------------+ 
4 rows in set (8.90 sec) 

我該如何改進這樣的查詢？

Answer 1

查看此查詢試試看。

SELECT u.*, t4.user_id, t4.data, t4.A, t4.ucount, u.userid AS IP 
FROM 
(
    select user_id, data, A, ucount, 
     @r := case when @g = USER_ID then @r+1 else 1 end rownum, 
     @g := user_id 
    from 
    (select @g:=null) g 
    cross join 
    (
    select t1.user_id, t1.data, ADDTIME(t1.data,'24:00:00') A, COUNT(*) ucount 
    from downloads t1 
    inner join downloads t2 on t1.user_id = t2.user_id 
         AND t1.data <= t2.data 
         AND ADDTIME(t1.data,'24:00:00') >= t2.data 
    GROUP BY t1.user_id, t1.data 
    HAVING COUNT(*) > 100 
    ORDER BY t1.user_id, ucount desc 
    ) t3 
) t4 
left join users u on u.id = t4.user_id 
where t4.rownum = 1