解决 SQL 问题绝对能让你对 MySQL 的理解更进一步

编辑: admin 分类: mysql 发布时间: 2023-06-10 来源:互联网

SQL教程栏目介绍如何更有效理解MySQL

解决 SQL 问题绝对能让你对 MySQL 的理解更进一步！

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属性表(product_props)结构如下

数据量800W以上

字段名类型说明idintidpn_idint属性类型pv_idint属性值product_idint产品ID

其中product_id与pn_id,pv_id是一对多的关系。
数据类似这样:

product_idpn_idpv_id109705 （型号）135 （苹果9）1097011 （内存）23 （512G）1097010 （颜色）17 （土豪金）109708 （网络）6（5G）109805135109801124 （1024G）109801016 （极光蓝）

产品表(product)结构如下

数据量40W以上

字段名类型说明product_idintproduct_idtype_idint类型idbrand_idint品牌idmodel_idint型号idstatustinyint状态

数据类似以下：

product_idtype_idbrand_idmodel_idstatus109701（手机）1(苹果)1(Iphone8)1(正常)109801（手机）1(苹果)1(Iphone8X)3(已售)109811（手机）1(苹果)1(Iphone8XP)1(正常)

问题

找出型号为苹果9同时内存为512G，颜色为土豪金，状态为正常的产品总数，
ps : 属性条件可能会有超过10组。

要求

性能第一，杜绝聚合函数等

原问题的解决方案性能排行

  1. 来自 @Kamicloud的 exist方案
SELECT 
    sql_no_cache `product_id`
FROM
    `zx_tests` AS a
WHERE
    `pn_id` = 101 AND `pv_id` = 59
        AND EXISTS( SELECT 
           sql_no_cache  *
        FROM
            `zx_tests`
        WHERE
        a.product_id = product_id and
            `pn_id` = 101 AND `pv_id` = 171);

    2 组条件下 0.657，3 组 0.695，4 组 0.759，5 组 0.743 （单独查属性表）
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  1. 来自 @Elijah_Wang的子查询方案
SELECT `product_id` FROM `product` WHERE `pn_id` = 5 AND `pv_id` = 135 AND `product_id` IN (SELECT `product_id` FROM `product` WHERE `pn_id` = 11 AND `pv_id` = 23);

    2 组条件下 0.729，3 组 0.75，4 组 0.730，5 组 0.757 (新问题之前)
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新问题之后的性能排行

  1. 来自 @Elijah_Wang的子查询方案
    select SQL_NO_CACHE count(1) from pdi_product a join  (
        SELECT
             distinct product_id
        FROM
            `product_props` 
        WHERE
            `pn_id` = 5 
            AND `pv_id` = 127
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 11 AND `pv_id` = 22 ) 
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 10 AND `pv_id` = 18 ) 
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 8 AND `pv_id` = 6 )  
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 9 AND `pv_id` = 1 )
            ) b on a.product_id = b.product_id 
            where  a.status = 1；
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耗时1.5-1.56 （执行10次的范围）

  • expain分析：

SQL 性能实战来了，机不可失！

        select SQL_NO_CACHE count(1) from pdi_product a 
            where  a.status = 1 and a.product_id in (SELECT
             distinct product_id
        FROM
            `product_props` 
        WHERE
            `pn_id` = 5 
            AND `pv_id` = 127
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 11 AND `pv_id` = 22 ) 
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 10 AND `pv_id` = 18 ) 
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 8 AND `pv_id` = 6 )  
            AND `product_id` IN ( SELECT  `product_id` FROM `product_props` WHERE `pn_id` = 9 AND `pv_id` = 1 ))
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耗时0.69-0.72（执行10次的范围）

  • explain分析：
    SQL 性能实战来了，机不可失！
  1. 来自 @Kamicloud的 exist方案
    SELECT SQL_NO_CACHE
            count(1) 
        FROM
            product a
        WHERE
            a.STATUS = 1 
            AND a.product_id IN (
        SELECT DISTINCT
            `product_id` 
        FROM
            `product_props` AS a 
        WHERE
            a.`pn_id` = 5 
            AND a.`pv_id` = 127 
            AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 11 AND `pv_id` = 22 ) 
            AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 10 AND `pv_id` = 18 ) 
            AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 9 AND `pv_id` = 1 ) 
            AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 8 AND `pv_id` = 6 ) 
            );
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耗时5.7-5.85 （执行10次的范围）

  • explain分析：

SQL 性能实战来了，机不可失！

    SELECT SQL_NO_CACHE
        count(1) 
    FROM
        pdi_product a
        join (SELECT DISTINCT
        `product_id` 
    FROM
        `product_props` AS a 
    WHERE
        a.`pn_id` = 5 
        AND a.`pv_id` = 127 
        AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 11 AND `pv_id` = 22 ) 
        AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 10 AND `pv_id` = 18 ) 
        AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 9 AND `pv_id` = 1 ) 
        AND EXISTS ( SELECT product_id FROM `product_props` WHERE a.product_id = product_id AND `pn_id` = 8 AND `pv_id` = 6 ) ) b
    on a.product_id = b.product_id
    WHERE
        a.STATUS = 1
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耗时5.7-6.0（执行10次的范围）

  • explain分析：

SQL 性能实战来了，机不可失！

可以看到如果单纯查属性表，第一位的速度是最快的，可要查产品状态后，速度反而不如子查询。

经explain分析，第一个子查询速度之所以快是因为它的sql简单，select_type皆为simple。

而不管是join还是exists的方式，select_type大多为DERIVED，DEPENDENT SUBQUERY。

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