MySQL 具有多个连接的查询

Question

我有很多联接的查询，我正在为其搜索优化。关于电脑：例如我有： Lenovo 8gbRAM 1TB core i5 ips 等（品牌名称后均为属性）我有配置，我想将属性 8gbRAM 更改为 16gbRAM，我必须搜索具有所有这些属性和 16gbRAM

的其他项目

两个表：

**st_item**
- id
- name
...

**st_item_specification_attribute**
- id
- st_item_id
- attribute_id
- attribute_value_id
...

我的问题是我的商品有 15 个属性。当我使用较少数量的属性进行测试时，我使用了这种查询结构并且它有效，但现在系统有 85k 个项目和超过 1kk 个项目属性这是查询：

SELECT `st_item`.id FROM `st_item` 
LEFT JOIN `st_item_specification_attribute` `sisa_36590` ON st_item.id = sisa_36590.item_id AND sisa_36590.attribute_id = 365 
LEFT JOIN `st_item_specification_attribute` `sisa_367910` ON st_item.id = sisa_367910.item_id AND sisa_367910.attribute_id = 367 
LEFT JOIN `st_item_specification_attribute` `sisa_374641` ON st_item.id = sisa_374641.item_id AND sisa_374641.attribute_id = 374 
LEFT JOIN `st_item_specification_attribute` `sisa_378366` ON st_item.id = sisa_378366.item_id AND sisa_378366.attribute_id = 378 
LEFT JOIN `st_item_specification_attribute` `sisa_382500` ON st_item.id = sisa_382500.item_id AND sisa_382500.attribute_id = 382 
LEFT JOIN `st_item_specification_attribute` `sisa_372134` ON st_item.id = sisa_372134.item_id AND sisa_372134.attribute_id = 372 
LEFT JOIN `st_item_specification_attribute` `sisa_41268` ON st_item.id = sisa_41268.item_id AND sisa_41268.attribute_id = 412 
LEFT JOIN `st_item_specification_attribute` `sisa_413368` ON st_item.id = sisa_413368.item_id AND sisa_413368.attribute_id = 413 
LEFT JOIN `st_item_specification_attribute` `sisa_414929` ON st_item.id = sisa_414929.item_id AND sisa_414929.attribute_id = 414 
LEFT JOIN `st_item_specification_attribute` `sisa_418496` ON st_item.id = sisa_418496.item_id AND sisa_418496.attribute_id = 418 
LEFT JOIN `st_item_specification_attribute` `sisa_385748` ON st_item.id = sisa_385748.item_id AND sisa_385748.attribute_id = 385 
LEFT JOIN `st_item_specification_attribute` `sisa_36625` ON st_item.id = sisa_36625.item_id AND sisa_36625.attribute_id = 366 
LEFT JOIN `st_item_specification_attribute` `sisa_366355` ON st_item.id = sisa_366355.item_id AND sisa_366355.attribute_id = 366 
LEFT JOIN `st_item_specification_attribute` `sisa_366816` ON st_item.id = sisa_366816.item_id AND sisa_366816.attribute_id = 366 
LEFT JOIN `st_item_specification_attribute` `sisa_366370` ON st_item.id = sisa_366370.item_id AND sisa_366370.attribute_id = 366 
WHERE (`parent_id`=1032) AND 
(sisa_36590.attribute_value_id = 2230) AND 
(sisa_367910.attribute_value_id = 2451) AND 
(sisa_374641.attribute_value_id = 3793) AND 
(sisa_378366.attribute_value_id = 2955) AND 
(sisa_382500.attribute_value_id = 3879) AND 
(sisa_372134.attribute_value_id = 2780) AND 
(sisa_41268.attribute_value_id = 3363) AND 
(sisa_413368.attribute_value_id = 3373) AND 
(sisa_414929.attribute_value_id = 3378) AND 
(sisa_418496.attribute_value_id = 3844) AND 
(sisa_385748.attribute_value_id = 3036) AND 
(sisa_36625.attribute_value_id = 2315) AND 
(sisa_366355.attribute_value_id = 2408) AND 
(sisa_366816.attribute_value_id = 2412) AND 
(sisa_366370.attribute_value_id = 2420)

查询必须比较特定的对 attribute_id => attribute_value_id，这就是我的“ON 子句”与 item_id 和 attribute_id 以及特定的 alias

的原因

Answer 1

您可以将您的 WHERE 条件移动到 ON 条件并将 LEFT JOIN 更改为 INNER JOIN.

SELECT `st_item`.id FROM `st_item` 
JOIN `st_item_specification_attribute` `sisa_36590` 
ON st_item.id = sisa_36590.item_id AND sisa_36590.attribute_id = 365
  AND sisa_36590.attribute_value_id = 2230 
JOIN `st_item_specification_attribute` `sisa_367910`
ON st_item.id = sisa_367910.item_id AND sisa_367910.attribute_id = 367 
 AND sisa_367910.attribute_value_id = 2451 
...
WHERE `parent_id`=1032

第二种方法

SELECT `st_item`.id FROM `st_item` 
JOIN `st_item_specification_attribute` `sisa` 
ON st_item.id = sisa.item_id AND 
  (
   (sisa.attribute_id = 365 AND sisa.attribute_value_id = 2230)
   OR
   (sisa.attribute_id = 367 AND sisa.attribute_value_id = 2451) 
    ...
  )
WHERE `parent_id`=1032
GROUP BY `st_item`.id
HAVING COUNT(*) = 15

Answer 2

您可以使用聚合：

select i.id
from st_item i join
     st_item_specification_attribute sisa
     ON sisa.item_id = i.item_id
where i.parent_id = 1032 and
      (sisa.attribute_id, attribute_value_id) in ( (365, 2230), (367, 2451), . . .)
group by i.id
having count(*) = 15;

Answer 3

我无法预测性能，但我认为您可以从所有联接中进行子选择

（我假设 atribute_id 和 Attribute_value_id 对在 item_id 中是唯一的）

SELECT `st_item`.id FROM `st_item` 
WHERE (`parent_id`=1032) AND 
  15 = (SELECT COUNT(*) FROM st_item_specification_attribute attr
         WHERE `st_item`.id = attr.item_id 
           AND (  attribute_id = 365 AND attribute_value_id = 2230 OR
                  ...
               )

Answer 4

我会为此使用 UNION ALL 方法。它很容易改变，而且相当容易阅读。性能应该也不错:

--A CTE so you only have to change parent_id in one place
--I believe not all mysql versions support this, though
--You could of course just select the parent_id in de UNION ALL and 
--   use a single WHERE in the outer query. 
WITH st_item_id AS
(
    SELECT  id
    ,       attribute_id
    ,       attribute_value_id
    FROM    st_item
    WHERE   parent_id = 1032
)

SELECT  UA.id
FROM    (
            SELECT  st_item.id 
            FROM    st_item_id 
            INNER JOIN st_item_specification_attribute sisa_36590 
                    ON st_item_id.id = sisa_36590.item_id 
                    AND sisa_36590.attribute_id = 365 
                    AND sisa_36590.attribute_value_id = 2230

            UNION ALL 

            SELECT  st_item.id 
            FROM    st_item_id 
            INNER JOIN st_item_specification_attribute sisa_367910 
                    ON st_item_id.id = sisa_367910.item_id 
                    AND sisa_367910.attribute_id = 367 
                    AND sisa_367910.attribute_value_id = 2451
        ) UA

MySQL 具有多个连接的查询

MySQL query with many joins

mysql

entity-attribute-value

第二种方法