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我正在解决一个运行很长时间的流程,这个select statemet运行超过30分钟,当我注释掉它的各个部分时,它运行速度非常快。我在表格旁边放置了一个看起来导致问题的表格,其中有两个**在Empid和ChangeDate上有一个聚集索引(这些列不相邻)不确定是否重要,也没有这些表格有超过3000行。我希望有一些简单的调整帽子需要作出。有什么我应该在源表中看看?任何建议,将不胜感激。我已经在Google搜索结果中使用了多个输入连接,但没有运气。为了排除故障我把与(NOLOCK)的。左连接导致头痛
select
je.EmpID,
max(med.ChangeDate) as Max_Medical_ChangeDate,
max(den.ChangeDate) as Max_Dental_ChangeDate,
max(k.ChangeDate) as Max_401K_ChangeDate,
max(ltd.ChangeDate) as Max_LTD_ChangeDate,
max(std.ChangeDate) as Max_STD_ChangeDate,
max(life.ChangeDate) as Max_Life_ChangeDate,
max(sal.ChangeDate) as Max_Salary_ChangeDate,
max(ltdexe.ChangeDate) as Max_LTDEXE_ChangeDate
max(accid.ChangeDate) as Max_Accid_ChangeDate,
max(cancr.ChangeDate) as Max_Cancr_ChangeDate,
max(hosp.ChangeDate) as Max_Hosp_ChangeDate
from Judge_Emp je WITH(NOLOCK)
left join Medical med on je.EmpID = med.EmpID
left join Dental den on med.EmpID = den.EmpID
left join R401K k on den.EmpID = k.EmpID
left join STDIns std on k.EmpID = std.EmpID
left join LTDIns ltd on std.EmpID = ltd.EmpID
* left join LTDEXEIns ltdexe on ltd.EmpID = ltdexe.EmpID
** left join LifeIns life on ltdexe.EmpID = life.EmpID
* left join Salary sal on life.EmpID = sal.EmpID
left join AF_Accid accid on accid.EmpID=sal.EmpID
left join AF_Cancr cancr on cancr.EmpID=accid.EmpID
left join AF_Hosp hosp on hosp.EmpID=cancr.EmpID
group by je.EmpID
感谢
你是什么意思“用于故障排除的目的我把(nolock)在”? –