Question

这是一个需要400秒加载的查询。我直接尝试了mysql。如果我单独尝试子查询，所有都会在不到0.01秒的时间内执行。在40秒内查询afer union所有exuecutes。联合之前的查询全部在1秒内执行。

sales表和salesaff表都包含大约12K条记录。此查询的目的是当sales = affiliate in sales table时，我需要添加salesaff表中的行，其中id与sales表中的搜索条件匹配。

 (
 SELECT 'no' AS aff, ss.orderid,ss.saletype,ss.price,ss.salests 
    FROM sales ss 
    WHERE 1=1 AND 
        ( ss.vendor='3kpertrade' OR ss.affiliate='3kpertrade') 
  ) 

 UNION ALL 

 ( 
 SELECT 'yes' AS aff, sf.orderid,sf.saletype,sf.price,sf.salests 
 FROM salesaff sf 
 WHERE sf.vendor=sf.affiliate AND 
 sf.orderid IN (SELECT ss.orderid from sales ss WHERE 1=1 
               AND ( ss.vendor='3kpertrade' OR ss.affiliate='3kpertrade') 
               GROUP BY ss.orderid ) 
 ) 

 ORDER BY salests DESC

Answer 1

尝试启动此功能：

EXPLAIN ( SELECT 'no' AS aff, ss.orderid,ss.saletype,ss.price,ss.salests FROM sales ss WHERE 1=1 AND ( ss.vendor='3kpertrade' OR ss.affiliate='3kpertrade') )

UNION ALL

( SELECT 'yes' AS aff, sf.orderid,sf.saletype,sf.price,sf.salests FROM salesaff sf WHERE sf.vendor=sf.affiliate AND

sf.orderid IN ( SELECT ss.orderid from sales ss WHERE 1=1 AND ( ss.vendor='3kpertrade' OR ss.affiliate='3kpertrade') GROUP BY ss.orderid ) )

ORDER BY salests DESC

检查“key”列是否永远不为null，否则将索引添加到提到的列中。

这没有用，请查看以下答案：https://dba.stackexchange.com/questions/7806/copying-to-tmp-table-extremely-slow

Answer 2

我认为它正在尝试在查询执行期间进行排序。这可能会有所帮助：

SELECT * FROM (
(
 SELECT 'no' AS aff, ss.orderid,ss.saletype,ss.price,ss.salests 
    FROM sales ss 
    WHERE 1=1 AND 
        ( ss.vendor='3kpertrade' OR ss.affiliate='3kpertrade') 
  ) 

 UNION ALL 

 ( 
 SELECT 'yes' AS aff, sf.orderid,sf.saletype,sf.price,sf.salests 
 FROM salesaff sf 
 WHERE sf.vendor=sf.affiliate AND 
 sf.orderid IN (SELECT ss.orderid from sales ss WHERE 1=1 
               AND ( ss.vendor='3kpertrade' OR ss.affiliate='3kpertrade') 
               GROUP BY ss.orderid ) 
 ) 
)
ORDER BY salests DESC

mysql查询需要400秒才能执行

2 个答案: