MariaDB 查询优化

如何解决MariaDB 查询优化

是否有任何选项可以优化此查询。它已经运行了将近4个小时，我仍然没有结果。表的当前行数为 282359

select c.id
from capacity_log c
where c.id = (
    select c1.id
    from capacity_log c1
     where  
        c1.date_occurred < '2020-10-1' 
        and c1.aux2 is null
        and c1.order_product_id = c.order_product_id
        and yearweek(c1.date_occurred) = yearweek(c.date_occurred)
    order by c1.used_capacity desc limit 1
)

想法是为每个order_product_id取每周最大使用容量列的id

CREATE TABLE `capacity_log` (
`id` INT UNSIGNED NOT NULL AUTO_INCREMENT,`date_occurred` DATETIME NOT NULL,`ip_address` VARCHAR(255) NOT NULL DEFAULT '',`order_product_id` INT UNSIGNED NOT NULL,`serial` VARCHAR(255) NOT NULL DEFAULT '',`used_capacity` BIGINT NULL DEFAULT NULL,`aux2` INT NULL DEFAULT NULL,`request` BLOB NULL,`retry_count` INT NOT NULL DEFAULT '0',`fetch_time` INT NOT NULL DEFAULT '0',`response` BLOB NULL,`custom_fetch_time` INT NOT NULL DEFAULT '0',PRIMARY KEY (`id`),INDEX `user_id` (`order_product_id`))




    +------+--------------------+-------+------+---------------+---------+---------+--------------------------------+--------+-----------------------------+
    | id   | select_type        | table | type | possible_keys | key     | key_len | ref                            | rows   | Extra                       |
    +------+--------------------+-------+------+---------------+---------+---------+--------------------------------+--------+-----------------------------+
    |    1 | PRIMARY            | c     | ALL  | NULL          | NULL    | NULL    | NULL                           | 390573 | Using where                 |
    |    2 | DEPENDENT SUBQUERY | c1    | ref  | user_id       | user_id | 4       | web_license.c.order_product_id |    134 | Using where; Using filesort |
    +------+--------------------+-------+------+---------------+---------+---------+--------------------------------+--------+-----------------------------+

版本：10.1.47-MariaDB-0+deb9u1

解决方法

使用窗口函数，需要升级到 MariaDB 10.2 或更高版本：

select t.id
from (
    select id,row_number() over (partition by order_product_id,yearweek(date_occurred) order by used_capacity desc) as rownum
    from capacity_log
    where date_occurred < '2020-10-1'
    and aux2 is null
) as t
where t.rownum = 1;

我认为以下索引将有助于此查询：

alter table capacity_log add index (aux2,date_occurred,order_product_id,used_capacity);

但我不使用 MariaDB，所以我没有对此进行测试。