SQL Server 2008-慢性能查询

Question

我在执行以下查询：

需要5分钟才能返回约68000条记录。但是，如果我从查询中删除LKP_PrivateSource（即最后一个左连接），则需要1秒才能返回68000条记录。 BTY，LKP_PrivateSource表中没有记录。任何想法是什么导致这个问题？

Select 
Case IsNull(LNK.StockID,0) 
    When 0 Then AE.StockID 
    Else LNK.StockID 
End StockID, 
IsNull(AE.LinkID,0) LinkID,IsNull(LNK.CapitalID,0) CapitalID,DE.SourceName 
,AE.SourceDate 'Date' 
,IsNull(AE.Formula,'') Formula 
From AE_RevenuData AE 
Left Join Linking LNK With(NoLock) ON LNK.LinkID=AE.LinkID 
Inner Join DE_DataEntities DE ON DE.EntityID=AE.EntityID 
Inner Join DataEntityIDs TE ON TE.EntityID=DE.EntityID 
Inner Join STG_LockedEntityData STG ON STG.StockID=IsNull(LNK.StockID,AE.StockID) AND STG.CapitalID=IsNull(LNK.CapitalID,0) 
Left Join LKP_PrivateSource PS ON IsNull(PS.PSourceId,0)=IsNull(AE.PSourceID,0) 
Where AE.ProjectID IN (13) 
AND AE.LinkID IS NOT NULL 

请参阅下面的计划：

|--Compute Scalar(DEFINE:([Expr1017]=CASE WHEN [Expr1026]=(0) THEN [MYDBNAME].[dbo].[AE_RevenueData].[StockID] as [AE].[StockID] ELSE [MYDBNAME].[dbo].[INV_InvestorFundLinking].[StockID] as [LNK].[StockID] END)) 
    |--Nested Loops(Left Outer Join, OUTER REFERENCES:([Expr1027])) 
     |--Filter(WHERE:([MYDBNAME].[dbo].[STG_LockedEntityData].[StockID] as [STG].[StockID]=isnull([MYDBNAME].[dbo].[INV_InvestorFundLinking].[StockID] as [LNK].[StockID],[MYDBNAME].[dbo].[AE_RevenueData].[StockID] as [AE].[StockID]) AND [MYDBNAME].[dbo].[STG_LockedEntityData].[CapitalID] as [STG].[CapitalID]=[Expr1019])) 
     | |--Compute Scalar(DEFINE:([Expr1019]=isnull([MYDBNAME].[dbo].[INV_InvestorFundLinking].[CapitalID] as [LNK].[CapitalID],(0)), [Expr1026]=isnull([MYDBNAME].[dbo].[INV_InvestorFundLinking].[StockID] as [LNK].[StockID],(0)))) 
     |   |--Nested Loops(Left Outer Join, OUTER REFERENCES:([AE].[LinkID])) 
     |    |--Nested Loops(Inner Join, WHERE:([MYDBNAME].[dbo].[AE_RevenueData].[LinkID] as [AE].[LinkID]=[MYDBNAME].[dbo].[STG_LockedEntityData].[LinkID] as [STG].[LinkID])) 
     |    | |--Sort(ORDER BY:([Expr1027] ASC)) 
     |    | | |--Hash Match(Inner Join, HASH:([TE].[EntityID])=([AE].[EntityID])) 
     |    | |   |--Nested Loops(Inner Join, OUTER REFERENCES:([Uniq1008], [DE].[ListingID])) 
     |    | |   | |--Nested Loops(Inner Join, OUTER REFERENCES:([TE].[EntityID])) 
     |    | |   | | |--Table Scan(OBJECT:([MYDBNAME].[dbo].[DataEntityIDs] AS [TE])) 
     |    | |   | | |--Index Seek(OBJECT:([MYDBNAME].[dbo].[DE_DataEntities].[PK_DE_DataSources] AS [DE]), SEEK:([DE].[EntityID]=[MYDBNAME].[dbo].[DataEntityIDs].[EntityID] as [TE].[EntityID]) ORDERED FORWARD) 
     |    | |   | |--Clustered Index Seek(OBJECT:([MYDBNAME].[dbo].[DE_DataEntities].[IX_DE_DataSources] AS [DE]), SEEK:([DE].[ListingID]=[MYDBNAME].[dbo].[DE_DataEntities].[ListingID] as [DE].[ListingID] AND [Uniq1008]=[Uniq1008]) LOOKUP ORDERED FORWARD) 
     |    | |   |--Compute Scalar(DEFINE:([Expr1018]=[MYDBNAME].[dbo].[AE_RevenueData].[LinkID] as [AE].[LinkID], [Expr1020]=isnull([MYDBNAME].[dbo].[AE_RevenueData].[Formula] as [AE].[Formula],''), [Expr1021]=CONVERT(bit,[MYDBNAME].[dbo].[AE_RevenueData].[IsSumOfFunds] as [AE].[IsSumOfFunds],0), [Expr1022]=isnull([MYDBNAME].[dbo].[AE_RevenueData].[ClientSpecificSource] as [AE].[ClientSpecificSource],N''), [Expr1023]=isnull([MYDBNAME].[dbo].[AE_RevenueData].[GenericSource] as [AE].[GenericSource],N''), [Expr1027]=isnull([MYDBNAME].[dbo].[AE_RevenueData].[PSourceID] as [AE].[PSourceID],(0)))) 
     |    | |    |--Clustered Index Seek(OBJECT:([MYDBNAME].[dbo].[AE_RevenueData].[IX_AE_RevenueData] AS [AE]), SEEK:([AE].[ProjectID]=(13)), WHERE:([MYDBNAME].[dbo].[AE_RevenueData].[LinkID] as [AE].[LinkID] IS NOT NULL) ORDERED FORWARD) 
     |    | |--Table Scan(OBJECT:([MYDBNAME].[dbo].[STG_LockedEntityData] AS [STG])) 
     |    |--Index Seek(OBJECT:([MYDBNAME].[dbo].[INV_InvestorFundLinking].[PK_Linking_1] AS [LNK]), SEEK:([LNK].[LinkID]=[MYDBNAME].[dbo].[AE_RevenueData].[LinkID] as [AE].[LinkID]) ORDERED FORWARD) 
     |--Clustered Index Seek(OBJECT:([MYDBNAME].[dbo].[LKP_PrivateSource].[PK_LKP_FactsetSource] AS [PS]), SEEK:([PS].[PSourceID]=[Expr1027]) ORDERED FORWARD) 

Answer 1

我认为这是事实，你正在使用在左边的两侧对比功能的加入。

如何解决它真的取决于业务逻辑，但我会考虑可能在该表上做两个或多个左连接。

一个用于值比较的直接值，另一个用于处理空值逻辑。

您需要将它们添加到您的聚结中，以便它们符合要求。