小编Leo*_*tta的帖子

我有一个SQL查询需要7分钟+返回结果.我正在尝试尽可能地优化,并且执行计划在Hash Match(Aggregate)上丢失了82%的时间.我做了一些搜索,看起来像使用"EXISTS"将有助于解决,但我还没有想出查询的语法,使其工作.这是查询:

select dbo.Server.Name,
                dbo.DiskSpace.Drive,
                AVG(dbo.DiskSpace.FreeSpace) as 'Free Disk Space',
                AVG(dbo.Processor.PercentUsed) as 'CPU % Used',
                AVG(dbo.Memory.PercentUtilized) as '% Mem Used'

                from Server
                join dbo.DiskSpace on dbo.Server.ID=DiskSpace.ServerID
                join dbo.Processor on dbo.Server.ID=Processor.ServerID
                join dbo.Memory on dbo.Server.ID=dbo.Memory.ServerID

                where
                dbo.Processor.ProcessorNum='_Total' 
                    and dbo.Processor.Datetm>DATEADD(DAY,-(1),(CONVERT (date, GETDATE()))) 
                    and (      dbo.Server.Name='qp-ratking' 
                            or dbo.Server.Name='qp-hyper2012' 
                            or dbo.Server.Name='qp-hyped' 
                            or dbo.Server.Name='qp-lichking')
                Group By dbo.server.name, Dbo.DiskSpace.Drive
                Order By Dbo.Server.Name, dbo.DiskSpace.Drive;

如何使用EXISTS减少/消除连接？或者,如果有更好的优化方法,我也会这样做.谢谢