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我试图优化我用来根据地址从数据库中获取客户的 mysql 查询。这个问题让我发疯，所以我会很感激帮助:)

我有两个与此查询相关的表：customers_address 和 systems_address。我只想获得具有我可以为该系统显示的地址的客户。

例子：

我想从customers_address表中获取客户，该表具有属于system_id 2的address_id。

使用 in 子句的最佳查询：

select distinct customer_id from customers_address use index(address_id_customer_id) where address_id in (select distinct address_id from systems_address where system_id = 2) and address_id !=-1\G;

事情是子查询只返回一行（值2），如果我用子查询值运行整个查询，它真的很快：

select customer_id from customers_address use index(address_id_customer_id) where address_id !=-1 and address_id in (2)\G;

时间从超过 10 秒下降到 0.00 秒。

我也尝试过使用连接进行查询，但是当我将值替换为 in 子句时，与查询相比，它的性能仍然很慢（超过 7 秒）。下面是带有连接的相同查询：

select distinct customer_id from customers_address use index(address_id_customer_id) inner join systems_address where systems_address.address_id = customers_address.address_id and system_id = 2 and customer_id != -1\G

我已将 customers_address 816 000 行和 systems_address 400 000 行放入。这些表的以下模式（表简化了该问题更容易找到）：

create table systems_address (
  `id` int(10) NOT NULL AUTO_INCREMENT PRIMARY KEY,
  `address_id` int(11) DEFAULT NULL,  
  `system_id` INTEGER(11)DEFAULT NULL,
   KEY `address_id` (address_id),
   KEY `system_id` (system_id))
  ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;

create table customers_address (
  `id` int(10) NOT NULL AUTO_INCREMENT PRIMARY KEY,
  `customer_id` int(11) DEFAULT NULL,  
  `address_id` INTEGER(11)DEFAULT NULL,
   KEY `customer_id` (customer_id),
   KEY `address_id` (address_id),
   KEY `address_id_customer_id` (address_id,customer_id),   
  FOREIGN KEY (`address_id`) REFERENCES `systems_address` (`address_id`) ON UPDATE CASCADE ON DELETE SET NULL)
  ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;

有什么方法可以让查询更快？？？

这是我运行 Bohemian 的查询时的解释结果（在创建这些新索引和更新之后）。

id:1
select_type: SIMPLE
table: 系统地址
类型: ref
possible_keys: address_id, system_id, address_id_system_id,idx1, key:idx1 key_len:5 ref:const rows:1999 Extra:Using where;Using Temporary

id:2
select_type:SIMPLE
table:customers_address
type:ref
possible_keys:customer_id, address_id, address_id_customer_id,idx2
key:address_id_customer_id
key_len:5
ref:database.systems_address.address_id
rows:45375
Extra: Using where;Using index

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1 回答 1

1

颠倒表的顺序并使用连接条件，其中包括额外条件：

select distinct customer_id
from systems_address
join customers_address on systems_address.address_id = customers_address.address_id
    and customer_id != -1
where system_id = 2

这应该执行得非常好，使用索引并最小化访问的行数。

确保您定义了以下索引：

create index idx1 on systems_address(system_id);
create index idx2 on customers_address(address_id);

可以肯定的是，还要更新统计信息：

analyze systems_address, customers_address;
于 2013-08-31T15:06:08.097 回答