Question

我正在运行一个通过日期范围搜索连接多个表的查询，并试图找出如何进一步优化它。

SELECT ACC.name AS account_name, CAMP.account_id AS account_id,CAMP.name AS campaign_name,CAMP.id AS campaign_id,ADG.id AS adgroup_id,ADG.name AS adgroup_name,KW.text AS keyword_name,
SUM(SPENT.billed_clicks) AS billed_clicks,KW.id AS keyword_id,KW.status_id AS status_id FROM account ACC, campaign CAMP,adgroup ADG,adgroup_keyword KW INNER JOIN keyword_spent SPENT
ON KW.id = SPENT.keyword_id WHERE     summary_date >= '2012-03-01' AND summary_date <= '2012-03-04' AND KW.adgroup_id = ADG.id AND ADG.campaign_id = CAMP.id AND CAMP.account_id = ACC.id
GROUP BY keyword_id

EXPLAIN on this产生以下内容 -

+----+-------------+-------+--------+----------------------------+--------------+---------+---------------------------------+--------+----------------------------------------------+
| id | select_type | table | type   | possible_keys              | key          | key_len | ref                             | rows   | Extra                                        |
+----+-------------+-------+--------+----------------------------+--------------+---------+---------------------------------+--------+----------------------------------------------+
|  1 | SIMPLE      | SPENT | range  | summary_date               | summary_date | 3       | NULL                            | 752191 | Using where; Using temporary; Using filesort | 
|  1 | SIMPLE      | KW    | eq_ref | PRIMARY,FK1948D0E6ED3A5544 | PRIMARY      | 8       | clicksummarydb.SPENT.keyword_id |      1 |                                              | 
|  1 | SIMPLE      | ADG   | eq_ref | PRIMARY,FKBBC2083C29112FD0 | PRIMARY      | 8       | advertisedb.KW.adgroup_id       |      1 |                                              | 
|  1 | SIMPLE      | CAMP  | eq_ref | PRIMARY,FKF7A90110246F33C4 | PRIMARY      | 8       | advertisedb.ADG.campaign_id     |      1 |                                              | 
|  1 | SIMPLE      | ACC   | eq_ref | PRIMARY                    | PRIMARY      | 8       | advertisedb.CAMP.account_id     |      1 |                                              | 
+----+-------------+-------+--------+----------------------------+--------------+---------+---------------------------------+--------+----------------------------------------------+

keyword_spent表包含超过150万行，这里是show create table

 | keyword_spent | CREATE TABLE `keyword_spent` (
   `id` bigint(20) NOT NULL auto_increment,
   `summary_date` date NOT NULL,
   `adgroup_id` bigint(20) NOT NULL,
   `keyword_id` bigint(20) NOT NULL,
   `billed_clicks` int(11) default NULL,
   `un_billed_clicks` int(11) default NULL,
   `spent` decimal(20,5) default NULL,
   `last_click_recno` bigint(20) default NULL,
   `campaign_id` bigint(20) NOT NULL,
   `account_id` bigint(20) NOT NULL,
   `total_convs` bigint(20) unsigned default '0',
    PRIMARY KEY  (`id`),
   UNIQUE KEY `keyword_spent_uniq` (`summary_date`,`adgroup_id`,`keyword_id`),
   KEY `idx_account_id` (`account_id`),
   KEY `idx_kw_id` (`keyword_id`),
   KEY `adgroup_id` (`adgroup_id`),
   KEY `campaign_id` (`campaign_id`),
   KEY `summary_date` (`summary_date`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

我不明白为什么当该日期范围内的记录不超过100,000条时，正在扫描750,000行。

另外，为什么它在做一个文件排序而不是使用索引。？

Answer 1

尝试连接谓词中引用的所有列的索引：

CREATE INDEX keyword_spent_IX2 ON keyword_spent (keyword_id, summary_date)

-OR -

CREATE INDEX keyword_spent_IX3 ON keyword_spent (summary_date, keyword_id)

- 或者 - 你甚至可以创建一个覆盖索引，其中包含查询中引用的所有列：

CREATE INDEX keyword_spent_IX4 ON keyword_spent (keyword_id, summary_date,
    billed_clicks, un_billed_clicks, spent, total_convs)

文件排序操作可能是由于GROUP BY。

我的偏好是使用JOIN ... ON语法而不是旧式逗号，并在WHERE子句中混合连接谓词。

  FROM account ACC
  JOIN campaign CAMP ON CAMP.account_id = ACC.id
  JOIN adgroup ADG ON ADG.campaign_id = CAMP.id
  JOIN adgroup_keyword KW ON KW.adgroup_id = ADG.id
  JOIN keyword_spent SPENT ON SPENT.keyword_id = KW.id
 WHERE SPENT.summary_date >= '2012-03-01'
   AND SPENT.summary_date <= '2012-03-04'
 GROUP BY SPENT.id

您只按SELECT列表中的非聚合子集进行分组。大多数其他RDBMS都会抛出异常; MySQL更自由。

Answer 2

文件排序不一定是坏事。如Baron Schwartz's blog post所示，文件排序不一定与文件有关。它只是在没有有效索引时使用的快速排序。

作为如何优化的想法：或许将所有聚合数据放在自己的子查询中，并加入该数据？我在想这样的事情（根据需要做出调整）：

SELECT ACC.name AS account_name,
CAMP.account_id AS account_id,
CAMP.name AS campaign_name,
CAMP.id AS campaign_id,
ADG.id AS adgroup_id,
ADG.name AS adgroup_name,
KW.text AS keyword_name,
KW.id AS keyword_id,
JOINED.billed_clicks AS billed_clicks,
JOINED.un_billed_clicks AS un_billed_clicks,
JOINED.total_clicks AS total_clicks,
JOINED.spent AS spent,
JOINED.total_convs AS total_convs
FROM account ACC
INNER JOIN campaign CAMP ON ACC.id = CAMP.account_id
INNER JOIN adgroup ADG ON CAMP.id = ADG.campaign_id
INNER JOIN adgroup_keyword KW ON ADG.id = KW.adgroup_id
INNER JOIN (SELECT
    SUM(billed_clicks) AS billed_clicks,
    SUM(un_billed_clicks) AS un_billed_clicks,
    SUM(billed_clicks) + SUM(un_billed_clicks) AS total_clicks,
    SUM(spent) AS spent,
    SUM(total_convs) AS total_convs,
    id AS keyword_id
    FROM keyword_spent
    GROUP BY keyword_id
) JOINED ON JOINED.keyword_id = KW.id

希望我理解这一点。这个解决方案有一个好处：group by / aggregates是分开的，你不必担心其他列的组，这是你在原始例子中从未做过的。

Answer 3

首先尝试使用summary_date上的索引（在where中使用），然后使用keyword_id;并在JOIN中明确移动日期范围：

ON (SPENT.id = KW.id AND SPENT.summary_date BETWEEN ... AND ...)

另外，尝试创建一个VIEW，为您提供SPENT上的聚合字段。理想情况下，优化器应该更好地理解这一点并节省您的时间。

CREATE VIEW SPENT AS SELECT
    keyword_id,
    SUM(SPENT.billed_clicks) AS billed_clicks,
    SUM(SPENT.un_billed_clicks) AS un_billed_clicks,
    SUM(SPENT.spent) AS spent,
    SUM(SPENT.total_convs) AS total_convs
FROM keyword_spent GROUP BY keyword_id;

这需要在keyword_id first和summary_date second上建立索引，而使用VIEW的JOIN应该等效于100,000行的SELECT。

mysql - 由于索引无效而避免使用filesort ..？

3 个答案: