Mysql超大分頁優化處理

Mysql超大分頁怎么優化處理

1）數據庫層面,這也是我們主要集中關注的(雖然收效沒那么大),類似於

select * from table where age > 20 limit 1000000,10

這種查詢其實也是有可以優化的余地的. 這條語句需要load1000000數據然后基本上全部丟棄,只取10條當然比較慢. 當時我們可以修改為

select * from table where id in (select id from table where age > 20 limit 1000000,10)

這樣雖然也load了一百萬的數據,但是由於索引覆蓋,要查詢的所有字段都在索引中,所以速度會很快. 同時如果ID連續的好(自增id連續),我們還可以

select * from table where id > 1000000 limit 10

效率也是不錯的,優化的可能性有許多種,但是核心思想都一樣,就是減少load的數據.

2）從需求的角度減少這種請求…主要是不做類似的需求(直接跳轉到幾百萬頁之后的具體某一頁.只允許逐頁查看或者按照給定的路線走,這樣可預測,可緩存)以及防止ID泄漏且連續被人惡意攻擊

3）分頁聯表left join優化

select * from sicimike where name like 'c6%' order by id limit 30000, 5;

可改為

select a.* from sicimike a inner join (select id from sicimike where name like 'c6%' order by id limit 30000, 5) b on a.id = b.id;

 效果展示

mysql> select a.* from sicimike a inner join (select id from sicimike where name like 'c6%' order by id limit 30000, 5) b on a.id = b.id;
+---------+------------+-----+---------------------+
| id      | name       | age | add_time            |
+---------+------------+-----+---------------------+
| 7466563 | c6db537243 |  59 | 2020-02-14 13:34:01 |
| 7466920 | c62dec7921 |  79 | 2020-02-14 13:34:01 |
| 7467162 | c610b89b31 |  71 | 2020-02-14 13:34:01 |
| 7467590 | c67bbd4bfd |  10 | 2020-02-14 13:34:01 |
| 7467825 | c6db24865b |  51 | 2020-02-14 13:34:01 |
+---------+------------+-----+---------------------+
5 rows in set (0.05 sec)

mysql> select * from sicimike where name like 'c6%' order by id limit 30000, 5;
+---------+------------+-----+---------------------+
| id      | name       | age | add_time            |
+---------+------------+-----+---------------------+
| 7466563 | c6db537243 |  59 | 2020-02-14 13:34:01 |
| 7466920 | c62dec7921 |  79 | 2020-02-14 13:34:01 |
| 7467162 | c610b89b31 |  71 | 2020-02-14 13:34:01 |
| 7467590 | c67bbd4bfd |  10 | 2020-02-14 13:34:01 |
| 7467825 | c6db24865b |  51 | 2020-02-14 13:34:01 |
+---------+------------+-----+---------------------+
5 rows in set (2.26 sec)