我的mysql关联查询/子查询很慢

[kevinworkroom]

查询一:
SELECT `order`.id,`order`.quantity
FROM `order` LEFT JOIN `coupon` ON `order`.id = coupon.order_id
WHERE `order`.team_id=162

查询二：
SELECT id,user_id,quantity ,(select count(id) FROM coupon where order_id=`order`.id) as sumq FROM `order` where `team_id`=162

这两个查询都很慢
查询结果是120条

表order约有4万条数据，表coupon约有5万条数据

[小小小小周]

`order`.team_id,`order`.id 上建立复合索引,要是order.id是主键了,则只需要在order.team_id上建立索引
coupon.order_id 建立索引

[我是csd_ner]

为什么慢？

[kevinworkroom]

存储引擎用MyISAM需要花1分以上的时间

用InnoDB要5-6秒

[rucypli]

explain看执行计划

[ACMAIN_CHM]

贴出你的
explain SELECT `order`.id,`order`.quantity
FROM `order` LEFT JOIN `coupon` ON `order`.id = coupon.order_id
WHERE `order`.team_id=162

explain SELECT id,user_id,quantity ,(select count(id) FROM coupon where order_id=`order`.id) as sumq FROM `order` where `team_id`=162

另外用 show index from tabl1 命令把相关表的索引情况贴出来以供分析。

[iihero_]

在coupon的order_id上创建索引
在order的order_id上创建索引
在order的team_id上创建索引

[zuoxingyu]

[Quote=引用 6 楼 acmain_chm 的回复:]
贴出你的
explain SELECT `order`.id,`order`.quantity
FROM `order` LEFT JOIN `coupon` ON `order`.id = coupon.order_id
WHERE `order`.team_id=162

explain SELECT id,user_id,quantity ,(select count(id) FR……
[/Quote]

这些是优化查询的基本信息，都要贴出来。

[mysqldbd]

[Quote=引用楼主 kevinworkroom 的回复:]
查询一:
SELECT `order`.id,`order`.quantity
FROM `order` LEFT JOIN `coupon` ON `order`.id = coupon.order_id
WHERE `order`.team_id=162

查询二：
SELECT id,user_id,quantity ,(select count(id) FROM coupon ……
[/Quote]

没有索引的，建立team_id、order_id组合做引，然后explain 2个sql语句，看看走没有走索引。

[kevinworkroom]

以下3条语句是在InnoDB存储引擎下执行
SELECT
id,
user_id,
quantity,
(SELECT
COUNT(id)
FROM coupon
WHERE order_id = `order`.id) AS countq
FROM `order`
WHERE `team_id` = 162
AND `order`.state = 'pay'
AND `order`.delivery = 'coupon'

用时3.594秒




SELECT
`order`.id,
`order`.quantity,
COUNT(coupon.id)
FROM `order`,
coupon
WHERE `order`.team_id = 162
AND `order`.state = 'pay'
AND `order`.delivery = 'coupon'
AND `order`.id = coupon.order_id
GROUP BY `order`.id
用时0.296秒




SELECT
`order`.id,
`order`.quantity,
COUNT(coupon.id)
FROM `order`
LEFT JOIN coupon
ON (`order`.id = coupon.order_id)
WHERE `order`.team_id = 162
AND `order`.state = 'pay'
AND `order`.delivery = 'coupon'
GROUP BY `order`.id

用时3.406秒

[kevinworkroom]

在MyISAM整个没有办法接受

[kevinworkroom]

EXPLAIN SELECT
`order`.id,
`order`.quantity,
COUNT(coupon.id)
FROM `order`,
coupon
WHERE `order`.team_id = 162
AND `order`.state = 'pay'
AND `order`.delivery = 'coupon'
AND `order`.id = coupon.order_id
GROUP BY `order`.id;


id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE coupon ALL 48154 Using temporary; Using filesort
1 SIMPLE order eq_ref PRIMARY PRIMARY 8 zuituan.coupon.order_id 1 Using where

[小小小小周]

[Quote=引用 12 楼 kevinworkroom 的回复:]
EXPLAIN SELECT
`order`.id,
`order`.quantity,
COUNT(coupon.id)
FROM `order`,
coupon
WHERE `order`.team_id = 162
AND `order`.state = 'pay'
AND `order`.delivery = 'coupon'
AND `order……
[/Quote]
coupon.order_id 这个字段上建立索引再看看explain;

[ACMAIN_CHM]

[Quote=引用 12 楼 kevinworkroom 的回复:]
EXPLAIN SELECT
`order`.id,
`order`.quantity,
COUNT(coupon.id)
FROM `order`,
coupon
WHERE `order`.team_id = 162
AND `order`.state = 'pay'
AND `order`.delivery = 'coupon'
AND `order……
[/Quote]

楼主似乎并不认真看别人的回复！
你的show index 都贴在哪儿了？

从你的EXPLAIN来看，你的表中似乎根本没有创建索引。