[英]Increase SQL Query Performance
Sql:
select distinct DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0) as Date,
(select count(*) from Raw_Mats A where DateAdd(Day, DateDiff(Day, 0, A.Receive_date), 0)=DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0)) as Total,
(select count(*) from Raw_Mats B where DateAdd(Day, DateDiff(Day, 0, B.Receive_date), 0)=DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0) and B.status='Solved') as Delivered,
(select count(*) from Raw_Mats C where DateAdd(Day, DateDiff(Day, 0, C.Receive_date), 0)=DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0) and C.status='Pending') as UnDelivered
from Raw_Mats m where m.Receive_date between '2011-07-01' and '2011-07-21'
如何提高上述查询的性能。 它需要 44 秒。 想让它少于 10 秒
谢谢
您对Receive_date
和status
都有索引吗? (不是每个的索引,合并)
还:
Delivered
和UnDelivered
子查询>=
和<=
这对于有时间的日期通常不正确为了清楚起见,我在这里使用了子查询,但这没关系:
select
DateOnly as Date,
COUNT(*) AS Total,
COUNT(CASE WHEN status='Solved' THEN 1 END) AS Delivered,
COUNT(CASE WHEN status='Pending' THEN 1 END) AS UnDelivered
from
(
SELECT
DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0) as DateOnly,
status
FROM
Raw_Mats
WHERE
Receive_date >= '2011-07-01' AND Receive_date < '2011-07-21'
) T
GROUP BY
DateOnly
编辑,没有子查询。
我从一个子查询开始,因为我认为它比预期的更复杂,并且没有费心把它拿出来......
select
DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0) as Date,
COUNT(*) AS Total,
COUNT(CASE WHEN status='Solved' THEN 1 END) AS Delivered,
COUNT(CASE WHEN status='Pending' THEN 1 END) AS UnDelivered
from
Raw_Mats
WHERE
Receive_date >= '2011-07-01' AND Receive_date < '2011-07-21'
GROUP BY
DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0)
分而治之:只需将 sql 的每个部分作为单独的语句尝试,您就会发现哪个部分慢。 如果您有子选择和功能,那么服务器很可能需要临时表来执行 select,如果您没有足够的 memory(或大型数据集或将您的 ZAC5C74B64B4B8352AF2F181 配置为服务器)临时对象被交换到磁盘,这也使它变慢。
太多子查询的人。 摆脱其中的一些,它会有所帮助。 此外,您不应该在 sql 的两边都使用函数。
例如:
where DateAdd(Day, DateDiff(Day, 0, A.Receive_date), 0)=
DateAdd(Day, DateDiff(Day, 0, m.Receive_date), 0)
在这种特定情况下,数据库引擎必须通过所有行 go 来评估DateDiff(Day, 0, A.Receive_date) and DateAdd(Day, DateDiff(Day, 0, A.Receive_date), 0)
然后将其与右手边也是 function。 这简直就是一场灾难。
另外,您在Receive_date
上有索引吗? 如果没有添加它。
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