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我是XQuery的新手。 请建议一种方法来优化以下查询。如何优化这个查询?
我已经尝试下面的查询它是花费比预期更多的时间。
Select
A.a_name,
I.p_type,
SUM(P.c_n_amount) AS c_n_amount,
CASE WHEN SUM(ABS(M_value)) = 0 THEN 0
ELSE SUM(ABS(Price) * ABS(M_value))/SUM(ABS(M_value)) END AS
[price],
SUM(M_value) AS m_value,SUM(N50) [-50],SUM(P50) [50]
from position P
INNER JOIN COUNT AS A ON P.a_id = A.a_id
INNER JOIN I_VIEW AS I ON P.i_id = I.i_id
inner join (
select R_C.p_id,M_value,Price,N50,P50
from(
select j.p_id,
C.value('(Result[@resultName = "m_value"]/resultValue)[1]', 'float') as M_value,
C.value('(Result[@resultName = "price"]/resultValue)[1]', 'float') as Price
from jyothi_xml j CROSS APPLY resultkeys.nodes('/Results') T(C)
where r_set='POLY' and r_category ='sk') R_Category,
(select j1.p_id,
C.value('(Result[@resultName = "rate_shock_n50"]/resultValue)[1]', 'float') as N50,
C.value('(Result[@resultName = "rate_shock_p50"]/resultValue)[1]', 'float') as P50
from jyothi_xml j1 CROSS APPLY resultkeys.nodes('/Results') T(C)
where result_set='POLY' and result_category ='rate_shocks') R_S_Category,position p
where p.p_id=R_Category.p_id and p.p_id=R_S_Category.p_id) XMlData on p.p_id=XMlData.p_id
WHERE P.as_of_date = '2012-10-10'
GROUP BY A.a_name, I.p_type
您操作的数据是什么?你期望的结果是什么?一般来说,在XQuery中,尽可能早地使用谓词是有利的,也就是说,不用(Result [@resultName =“m_value”]/resultValue)[1] use(Result [@resultName =“m_value”] [1]/resultValue)。但是,我猜XQuery并不是这里的瓶颈。相反,你有一个相当昂贵的SQL与联合,聚合和subquerys。相比之下,你的XQuery似乎是简单的数据提取。请首先检查一下,XQuery确实是这里的问题。 – dirkk