Question

一旦表格完全填充，我就会担心下面的查询的性能。到目前为止，它正在开发中，并且可以很好地处理虚拟数据。

表“adress_zoo”将在完全填充后包含大约5亿条记录。 “adress_zoo”表看起来像这样：

  CREATE TABLE `adress_zoo` 
     ( `adress_id` int(11) NOT NULL, `zoo_id` int(11) NOT NULL, 
     UNIQUE KEY `pk` (`adress_id`,`zoo_id`), 
     KEY `adress_id` (`adress_id`) ) 
     ENGINE=InnoDB DEFAULT CHARSET=latin1;

其他表格每个最多包含500条记录。

完整查询如下所示：

  SELECT a.* FROM jos_zoo_item AS a 
  JOIN jos_zoo_search_index AS zsi2 ON zsi2.item_id = a.id 
  WHERE a.id IN (   

     SELECT r.id FROM ( 

        SELECT zi.id AS id, Max(zi.priority) as prio 
        FROM jos_zoo_item AS zi 
        JOIN jos_zoo_search_index AS zsi ON zsi.item_id = zi.id 
        LEFT JOIN jos_zoo_tag AS zt ON zt.item_id = zi.id 
        JOIN jos_zoo_category_item AS zci ON zci.item_id = zi.id 
        **JOIN adress_zoo AS az ON az.zoo_id = zi.id** 

        WHERE 1=1 
        AND ( (zci.category_id != 0 AND ( zt.name != 'prolong' OR zt.name is NULL)) 
        OR (zci.category_id = 0 AND zt.name = 'prolong') ) 
        AND zi.type = 'telefoni' 
        AND zsi.element_id = '44d3b1fd-40f6-4fd7-9444-7e11643e2cef' 
        AND zsi.value = 'Small' 
        AND zci.category_id > 15 
        **AND az.adress_id = 5** 

        GROUP BY zci.category_id ) AS r 
  ) 

  AND a.application_id = 6 
  AND a.access IN (1,1) 
  AND a.state = 1 
  AND (a.publish_up = '0000-00-00 00:00:00' OR a.publish_up <= '2012-06-07 07:51:26') 
  AND (a.publish_down = '0000-00-00 00:00:00' OR a.publish_down >= '2012-06-07 07:51:26') 
  AND zsi2.element_id = '1c3cd26e-666d-4f8f-a465-b74fffb4cb14' 

  GROUP BY a.id 
  ORDER BY zsi2.value ASC

查询通常会返回大约25条记录。

根据您的经验，此查询是否可以接受（在3秒内响应）？我该怎么做才能优化它？

正如@Jack所建议的那样，我使用EXPLAIN运行查询并得到了这个：

MySQL EXPLAIN output

Answer 1

这部分是一个重要的限制因素：

az.adress_id = 5

MySQL会将表限制为adress_id与匹配的记录将其与语句的其余部分连接起来，因此它取决于您认为结果集可能有多大

顺便说一下，您有一个UNIQUE(adress_id, zoo_id)和一个单独的INDEX。有什么特别的原因吗？因为MySQL可以使用生成密钥的第一部分来选择。

同样重要的是使用EXPLAIN来了解MySQL如何“攻击”您的查询并返回结果。另见：http://dev.mysql.com/doc/refman/5.5/en/execution-plan-information.html

Answer 2

为避免子查询，您可以尝试将查询重写为：

SELECT a.* FROM jos_zoo_item AS a 
  JOIN jos_zoo_search_index AS zsi2 ON zsi2.item_id = a.id 
  INNER JOIN 
  (   
     SELECT ** distinct ** r.id FROM ( 

        SELECT zi.id AS id, Max(zi.priority) as prio 
        FROM jos_zoo_item AS zi 
        JOIN jos_zoo_search_index AS zsi ON zsi.item_id = zi.id 
        LEFT JOIN jos_zoo_tag AS zt ON zt.item_id = zi.id 
        JOIN jos_zoo_category_item AS zci ON zci.item_id = zi.id 
        **JOIN adress_zoo AS az ON az.zoo_id = zi.id** 

        WHERE 1=1 
        AND ( (zci.category_id != 0 AND ( zt.name != 'prolong' OR zt.name is NULL)) 
        OR (zci.category_id = 0 AND zt.name = 'prolong') ) 
        AND zi.type = 'telefoni' 
        AND zsi.element_id = '44d3b1fd-40f6-4fd7-9444-7e11643e2cef' 
        AND zsi.value = 'Small' 
        AND zci.category_id > 15 
        **AND az.adress_id = 5** 

        GROUP BY zci.category_id ) AS r 
  ) T
    on a.id = T.id
  where 
  AND a.application_id = 6 
  AND a.access IN (1,1) 
  AND a.state = 1 
  AND (a.publish_up = '0000-00-00 00:00:00' OR a.publish_up <= '2012-06-07 07:51:26') 
  AND (a.publish_down = '0000-00-00 00:00:00' OR a.publish_down >= '2012-06-07 07:51:26') 
  AND zsi2.element_id = '1c3cd26e-666d-4f8f-a465-b74fffb4cb14' 

  GROUP BY a.id 
  ORDER BY zsi2.value ASC

此方法不会为每个候选行执行子查询。只有在几毫秒内计算T时，性能才会提高。

MySQL中的500万行表在select中加入了查询

2 个答案: