在优化以下查询(示例1)时,我一直感到困扰:
SELECT `service`.*
FROM
(
SELECT `storeUser`.`storeId`
FROM `storeUser`
WHERE `storeUser`.`userId` = 1
UNION
SELECT `store`.`storeId`
FROM `companyUser`
INNER JOIN `store` ON `companyUser`.`companyId` = `store`.`companyId`
WHERE `companyUser`.`userId` = 1
UNION
SELECT `store`.`storeId`
FROM `accountUser`
INNER JOIN `company` ON `company`.`accountId` = `accountUser`.`accountId`
INNER JOIN `store` ON `company`.`companyId` = `store`.`companyId`
WHERE `accountUser`.`userId` = 1
) AS `storeUser`
INNER JOIN `service` ON `storeUser`.`storeId` = `service`.`storeId`
LIMIT 10;
子查询应该返回类似"1"、"2"、"3"、"4"这样的内容。无论如何,它非常缓慢,需要约48秒才能给出响应,尽管该子查询本身在另一个控制台中运行只需约0.0020毫秒即可给出结果。如果将子查询放在IN语句中(示例2),情况也是一样的。
SELECT `service`.*
FROM `service`
WHERE 1
AND `service`.`storeId` IN (
SELECT `storeUser`.`storeId` FROM `storeUser` WHERE `storeUser`.`userId` = 1
UNION
SELECT `store`.`storeId` FROM `companyUser`
INNER JOIN `store` ON `companyUser`.`companyId` = `store`.`companyId`
WHERE `companyUser`.`userId` = 1
UNION
SELECT `store`.`storeId`
FROM `accountUser`
INNER JOIN `company` ON `company`.`accountId` = `accountUser`.`accountId`
INNER JOIN `store` ON `company`.`companyId` = `store`.`companyId`
WHERE `accountUser`.`userId` = 1
)
LIMIT 10;
但是,如果我手动输入查询返回的值,它基本上是立即响应的:
SELECT
`service`.*
FROM
`service`
WHERE 1
AND `service`.`storeId` IN (
"1", "2", "3", "4", "5"
)
LIMIT 10;
需要重要提到的是,我已经检查了连接中的索引,一切似乎都就位了,而且“EXPLAIN [query]”返回的筛选分数基本上都是100分。
编辑:
之前没有提供足够的信息,很抱歉,希望这次可以更有帮助:
MySQL 5.7,
Storage engine: InnoDB
EXPLAINs
1.) StoreUser
id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra
1 | SIMPLE | storeUser | NULL | ref | PRIMARY, storeUserUser | PRIMARY | 4 | const | 1 |100.00 | Using index
2.) CompanyUser
id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra
1 | SIMPLE | companyUser | NULL | ref | PRIMARY,companyUserCompany,companyUserUser | companyUserUser | 4 | const | 30 | 100.00 | Using index
1 | SIMPLE | store | NULL | ref | storeCompany | storeCompany | 4 | Table.companyUser.companyId | 5 | 100.00 | Using index
3.) AccountUser
id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra
1 | SIMPLE | accountUser | NULL | ref | PRIMARY,accountUserUser | accountUserUser | 4 | const | 1 | 100.00 | Using index
1 | SIMPLE | company | NULL | ref | PRIMARY,companyAccount | companyAccount | 4 | Table.accountUser.accountId | 305 | 100.00 | Using index
1 | SIMPLE | store | NULL | ref | storeCompany | storeCompany | 4 | Table.company.companyId | 5 | 100.00 | Using index
4.) Whole query (Example 2)
id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra
1 | PRIMARY | service | NULL | ALL | NULL | NULL | NULL | NULL | 2836046 | 100.00 | Using where
2 | DEPENDENT SUBQUERY | storeUser | NULL | eq_ref | PRIMARY,storeUserStore,storeUserUser | PRIMARY | 8 | const,func | 1 | 100.00 | Using index
3 | DEPENDENT UNION | store | NULL | eq_ref | PRIMARY,storeCompany | PRIMARY | 4 | func | 1 | 100.00 | NULL
3 | DEPENDENT UNION | companyUser | NULL | eq_ref | PRIMARY,companyUserCompany,companyUserUser | PRIMARY | 8 | const,Table.store.companyId | 1 | 100.00 | Using index
4 | DEPENDENT UNION | companyUser | NULL | ref | PRIMARY,accountUserUser | accountUserUser | 4 | const | 1 | 100.00 | Using index
4 | DEPENDENT UNION | store | NULL | eq_ref | PRIMARY,storeCompany | PRIMARY | 4 | func | 1 | 100.00 | NULL
4 | DEPENDENT UNION | company | NULL | eq_ref | PRIMARY,companyAccount | PRIMARY | 4 | Table.store.companyId | 1 | 100.00 | Using where
NULL | UNION RESULT | <union2,3,4>| NULL | ALL | NULL | NULL | NULL | NULL | NULL | NULL | Using temporary
service
集成到 UNION 的每个子查询中,分别优化每个子查询,然后 UNION,对它们的输出进行 ORDER BY 和 LIMIT。 - Akina