SQL Server中，SELECT

的奇怪行为我有两个表：dim_applications随着应用SQL Server中，SELECT

/*dim_applications*/ 
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[dim_applications]') AND type in (N'U')) 
BEGIN 
    CREATE TABLE [dbo].[dim_applications](
     [id] [bigint] NOT NULL, 
     [country_id] [int] NOT NULL, 
     [customer_id] [bigint] NOT NULL, 
     [first_status_day_date] [date] NULL, 
     [first_status_time_of_day] [time](0) NULL, 
     [campaign_id] [int] NULL, 
     [campaign_response_time][int] NULL 
    ) ON [PRIMARY] 
END 
GO 

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE object_id = OBJECT_ID(N'[dbo].[dim_applications]') AND name = N'PK_dim_applications') 
ALTER TABLE [dbo].[dim_applications] ADD CONSTRAINT [PK_dim_applications] PRIMARY KEY CLUSTERED 
(
    [id] ASC 
) 
GO 

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE object_id = OBJECT_ID(N'[dbo].[dim_applications]') AND name = N'IX_dim_applications') 
CREATE NONCLUSTERED INDEX [IX_dim_applications] ON [dbo].[dim_applications] 
(
    [country_id] ASC 
) 
INCLUDE ([customer_id], [first_status_day_date], [first_status_time_of_day]) 
GO

列表和日志表发送给客户的CRM信息：

IF NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'dbo' AND TABLE_NAME = 'fact_customers_campaigns' AND TABLE_CATALOG = 'dwh') 
BEGIN 
    CREATE TABLE [dbo].[fact_customers_campaigns](
     [campaign_id] [int] NOT NULL, 
     [customer_id] [bigint] NULL, 
     [day_date] [date] NOT NULL, 
     [time_of_day] [time](0) NOT NULL 
     ) ON [PRIMARY] 
END 
GO 

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE object_id = OBJECT_ID(N'[dbo].[fact_customers_campaigns]') AND name = N'IX_fact_customers_campaigns_3') 
CREATE NONCLUSTERED INDEX [IX_fact_customers_campaigns_3] ON [dbo].[fact_customers_campaigns] 
(
    [customer_id] ASC, 
    [day_date] DESC, 
    [time_of_day] DESC 
) 
INCLUDE([campaign_id]) 
WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
GO

我想选择什么是针对特定国家/地区的每个应用程序最近的广告系列的“campaign_id”。此广告系列不得超过14天。两个表的连接由“customer_id”完成。

我选择查询是这样

SELECT 
    a.id 
    ,(SELECT TOP 1 
      c.campaign_id 
     FROM [dwh].[dbo].[fact_customers_campaigns] c 
     WHERE 1 = 1 
      AND c.[customer_id] = a.[customer_id] 
      AND DATEDIFF(DD, c.[day_date], a.[first_status_day_date]) BETWEEN 0 AND 14 
      ORDER BY c.[day_date] DESC, c.[time_of_day] DESC) 
FROM [dwh].[dbo].[dim_applications] a 
WHERE 1 = 1 
    AND a.[country_id] = 1

它工作正常，在7秒内返回150万分的记录。但是，当我在列表（14）中使用最后一个国家/地区的country_id运行相同的查询时，同样的查询变得非常缓慢，可能需要长达2分钟（120万条记录）。为什么会有这样的差异？计划是一样的。我只是不明白这种行为。服务器版本

Microsoft SQL Server 2012 (SP1) - 11.0.3339.0 (X64) 
    Jan 14 2013 19:02:10 
    Copyright (c) Microsoft Corporation 
    Developer Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1)

和

Microsoft SQL Server 2008 R2 (SP1) - 10.50.2796.0 (X64) 
    Dec 9 2011 11:27:20 
    Copyright (c) Microsoft Corporation 
    Standard Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1) (Hypervisor)

我怎样才能让执行时间是独立选择的county_id的？这里是COUNTRY_ID = 14时，SQL Server 2012 SP1

<?xml version="1.0" encoding="utf-16"?> 
<ShowPlanXML xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" Version="1.2" Build="11.0.3339.0" xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan"> 
    <BatchSequence> 
    <Batch> 
     <Statements> 
     <StmtSimple StatementCompId="1" StatementEstRows="1253920" StatementId="1" StatementOptmLevel="FULL" StatementSubTreeCost="258.447" StatementText="SELECT &#xD;&#xA; a.id&#xD;&#xA; ,(SELECT TOP 1 &#xD;&#xA;   c.campaign_id &#xD;&#xA;  FROM [dwh].[dbo].[fact_customers_campaigns] c &#xD;&#xA;  WHERE 1 = 1&#xD;&#xA;   AND c.[customer_id] = a.[customer_id] &#xD;&#xA;   AND DATEDIFF(DD, c.[day_date], a.[first_status_day_date]) BETWEEN 0 AND 14&#xD;&#xA;   ORDER BY c.[day_date] DESC, c.[time_of_day] DESC)&#xD;&#xA;FROM [dwh].[dbo].[dim_applications] a&#xD;&#xA;WHERE 1 = 1&#xD;&#xA; AND a.[country_id] = 14" StatementType="SELECT" QueryHash="0x9FA79BEF6AA009EB" QueryPlanHash="0x98FC15D00C35255D" RetrievedFromCache="true"> 
      <StatementSetOptions ANSI_NULLS="true" ANSI_PADDING="true" ANSI_WARNINGS="true" ARITHABORT="true" CONCAT_NULL_YIELDS_NULL="true" NUMERIC_ROUNDABORT="false" QUOTED_IDENTIFIER="true" /> 
      <QueryPlan DegreeOfParallelism="8" MemoryGrant="136" CachedPlanSize="40" CompileTime="2" CompileCPU="2" CompileMemory="488"> 
      <ThreadStat Branches="1" UsedThreads="8"> 
       <ThreadReservation NodeId="0" ReservedThreads="8" /> 
      </ThreadStat> 
      <MemoryGrantInfo SerialRequiredMemory="0" SerialDesiredMemory="0" RequiredMemory="136" DesiredMemory="136" RequestedMemory="136" GrantWaitTime="0" GrantedMemory="136" MaxUsedMemory="136" /> 
      <OptimizerHardwareDependentProperties EstimatedAvailableMemoryGrant="314572" EstimatedPagesCached="157286" EstimatedAvailableDegreeOfParallelism="4" /> 
      <RelOp AvgRowSize="19" EstimateCPU="0.125392" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="1253920" LogicalOp="Compute Scalar" NodeId="0" Parallel="false" PhysicalOp="Compute Scalar" EstimatedTotalSubtreeCost="258.447"> 
       <OutputList> 
       <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
       <ColumnReference Column="Expr1006" /> 
       </OutputList> 
       <ComputeScalar> 
       <DefinedValues> 
        <DefinedValue> 
        <ColumnReference Column="Expr1006" /> 
        <ScalarOperator ScalarString="[dwh].[dbo].[fact_customers_campaigns].[campaign_id] as [c].[campaign_id]"> 
         <Identifier> 
         <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
         </Identifier> 
        </ScalarOperator> 
        </DefinedValue> 
       </DefinedValues> 
       <RelOp AvgRowSize="19" EstimateCPU="0.940258" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="1253920" LogicalOp="Gather Streams" NodeId="1" Parallel="true" PhysicalOp="Parallelism" EstimatedTotalSubtreeCost="258.322"> 
        <OutputList> 
        <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
        <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
        </OutputList> 
        <RunTimeInformation> 
        <RunTimeCountersPerThread Thread="0" ActualRows="1253922" ActualEndOfScans="1" ActualExecutions="1" /> 
        </RunTimeInformation> 
        <Parallelism> 
        <RelOp AvgRowSize="19" EstimateCPU="1.31035" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="1253920" LogicalOp="Left Outer Join" NodeId="2" Parallel="true" PhysicalOp="Nested Loops" EstimatedTotalSubtreeCost="257.382"> 
         <OutputList> 
         <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
         <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
         </OutputList> 
         <RunTimeInformation> 
         <RunTimeCountersPerThread Thread="4" ActualRows="86240" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="8" ActualRows="219041" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="5" ActualRows="172480" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="3" ActualRows="86241" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="7" ActualRows="258720" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="6" ActualRows="172480" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="1" ActualRows="172480" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="2" ActualRows="86240" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
         <RunTimeCountersPerThread Thread="0" ActualRows="0" ActualEndOfScans="0" ActualExecutions="0" /> 
         </RunTimeInformation> 
         <NestedLoops Optimized="false" WithUnorderedPrefetch="true"> 
         <OuterReferences> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="customer_id" /> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="first_status_day_date" /> 
          <ColumnReference Column="Expr1008" /> 
         </OuterReferences> 
         <RelOp AvgRowSize="26" EstimateCPU="0.344868" EstimateIO="4.14941" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="1253920" LogicalOp="Index Seek" NodeId="4" Parallel="true" PhysicalOp="Index Seek" EstimatedTotalSubtreeCost="4.49428" TableCardinality="6016420"> 
          <OutputList> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="customer_id" /> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="first_status_day_date" /> 
          </OutputList> 
          <RunTimeInformation> 
          <RunTimeCountersPerThread Thread="8" ActualRows="219041" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="4" ActualRows="86240" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="5" ActualRows="172480" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="3" ActualRows="86241" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="7" ActualRows="258720" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="6" ActualRows="172480" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="1" ActualRows="172480" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="2" ActualRows="86240" Batches="0" ActualEndOfScans="1" ActualExecutions="1" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="0" ActualRows="0" ActualEndOfScans="0" ActualExecutions="0" /> 
          </RunTimeInformation> 
          <IndexScan Ordered="true" ScanDirection="FORWARD" ForcedIndex="false" ForceSeek="false" ForceScan="false" NoExpandHint="false" Storage="RowStore"> 
          <DefinedValues> 
           <DefinedValue> 
           <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
           </DefinedValue> 
           <DefinedValue> 
           <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="customer_id" /> 
           </DefinedValue> 
           <DefinedValue> 
           <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="first_status_day_date" /> 
           </DefinedValue> 
          </DefinedValues> 
          <Object Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Index="[IX_dim_applications]" Alias="[a]" IndexKind="NonClustered" /> 
          <SeekPredicates> 
           <SeekPredicateNew> 
           <SeekKeys> 
            <Prefix ScanType="EQ"> 
            <RangeColumns> 
             <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="country_id" /> 
            </RangeColumns> 
            <RangeExpressions> 
             <ScalarOperator ScalarString="(14)"> 
             <Const ConstValue="(14)" /> 
             </ScalarOperator> 
            </RangeExpressions> 
            </Prefix> 
           </SeekKeys> 
           </SeekPredicateNew> 
          </SeekPredicates> 
          </IndexScan> 
         </RelOp> 
         <RelOp AvgRowSize="11" EstimateCPU="1E-07" EstimateIO="0" EstimateRebinds="1253920" EstimateRewinds="0.134582" EstimatedExecutionMode="Row" EstimateRows="1" LogicalOp="Top" NodeId="5" Parallel="true" PhysicalOp="Top" EstimatedTotalSubtreeCost="251.577"> 
          <OutputList> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
          </OutputList> 
          <RunTimeInformation> 
          <RunTimeCountersPerThread Thread="4" ActualRows="0" Batches="0" ActualEndOfScans="86240" ActualExecutions="86240" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="8" ActualRows="36405" Batches="0" ActualEndOfScans="182636" ActualExecutions="219041" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="5" ActualRows="11849" Batches="0" ActualEndOfScans="160631" ActualExecutions="172480" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="3" ActualRows="1367" Batches="0" ActualEndOfScans="84874" ActualExecutions="86241" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="7" ActualRows="47272" Batches="0" ActualEndOfScans="211448" ActualExecutions="258720" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="6" ActualRows="22849" Batches="0" ActualEndOfScans="149631" ActualExecutions="172480" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="1" ActualRows="19968" Batches="0" ActualEndOfScans="152512" ActualExecutions="172480" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="2" ActualRows="0" Batches="0" ActualEndOfScans="86240" ActualExecutions="86240" ActualExecutionMode="Row" /> 
          <RunTimeCountersPerThread Thread="0" ActualRows="0" ActualEndOfScans="0" ActualExecutions="0" /> 
          </RunTimeInformation> 
          <Top RowCount="false" IsPercent="false" WithTies="false"> 
          <TopExpression> 
           <ScalarOperator ScalarString="(1)"> 
           <Const ConstValue="(1)" /> 
           </ScalarOperator> 
          </TopExpression> 
          <RelOp AvgRowSize="25" EstimateCPU="0.000167189" EstimateIO="0.003125" EstimateRebinds="1253920" EstimateRewinds="0.134582" EstimatedExecutionMode="Row" EstimateRows="1" LogicalOp="Index Seek" NodeId="7" Parallel="true" PhysicalOp="Index Seek" EstimatedTotalSubtreeCost="229.491" TableCardinality="1606160"> 
           <OutputList> 
           <ColumnReference Column="Bmk1002" /> 
           <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
           <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="day_date" /> 
           <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="time_of_day" /> 
           </OutputList> 
           <RunTimeInformation> 
           <RunTimeCountersPerThread Thread="4" ActualRows="0" Batches="0" ActualEndOfScans="86240" ActualExecutions="86240" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="8" ActualRows="36405" Batches="0" ActualEndOfScans="182636" ActualExecutions="219041" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="5" ActualRows="11849" Batches="0" ActualEndOfScans="160631" ActualExecutions="172480" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="3" ActualRows="1367" Batches="0" ActualEndOfScans="84874" ActualExecutions="86241" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="7" ActualRows="47272" Batches="0" ActualEndOfScans="211448" ActualExecutions="258720" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="6" ActualRows="22849" Batches="0" ActualEndOfScans="149631" ActualExecutions="172480" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="1" ActualRows="19968" Batches="0" ActualEndOfScans="152512" ActualExecutions="172480" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="2" ActualRows="0" Batches="0" ActualEndOfScans="86240" ActualExecutions="86240" ActualExecutionMode="Row" /> 
           <RunTimeCountersPerThread Thread="0" ActualRows="0" ActualEndOfScans="0" ActualExecutions="0" /> 
           </RunTimeInformation> 
           <IndexScan Ordered="true" ScanDirection="FORWARD" ForcedIndex="false" ForceSeek="false" ForceScan="false" NoExpandHint="false" Storage="RowStore"> 
           <DefinedValues> 
            <DefinedValue> 
            <ColumnReference Column="Bmk1002" /> 
            </DefinedValue> 
            <DefinedValue> 
            <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
            </DefinedValue> 
            <DefinedValue> 
            <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="day_date" /> 
            </DefinedValue> 
            <DefinedValue> 
            <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="time_of_day" /> 
            </DefinedValue> 
           </DefinedValues> 
           <Object Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Index="[IX_fact_customers_campaigns_3]" Alias="[c]" IndexKind="NonClustered" /> 
           <SeekPredicates> 
            <SeekPredicateNew> 
            <SeekKeys> 
             <Prefix ScanType="EQ"> 
             <RangeColumns> 
              <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="customer_id" /> 
             </RangeColumns> 
             <RangeExpressions> 
              <ScalarOperator ScalarString="[dwh].[dbo].[dim_applications].[customer_id] as [a].[customer_id]"> 
              <Identifier> 
               <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="customer_id" /> 
              </Identifier> 
              </ScalarOperator> 
             </RangeExpressions> 
             </Prefix> 
            </SeekKeys> 
            </SeekPredicateNew> 
           </SeekPredicates> 
           <Predicate> 
            <ScalarOperator ScalarString="datediff(day,CONVERT_IMPLICIT(datetimeoffset(7),[dwh].[dbo].[fact_customers_campaigns].[day_date] as [c].[day_date],0),CONVERT_IMPLICIT(datetimeoffset(7),[dwh].[dbo].[dim_applications].[first_status_day_date] as [a].[first_status_day_date],0))&gt;=(0) AND datediff(day,CONVERT_IMPLICIT(datetimeoffset(7),[dwh].[dbo].[fact_customers_campaigns].[day_date] as [c].[day_date],0),CONVERT_IMPLICIT(datetimeoffset(7),[dwh].[dbo].[dim_applications].[first_status_day_date] as [a].[first_status_day_date],0))&lt;=(14)"> 
            <Logical Operation="AND"> 
             <ScalarOperator> 
             <Compare CompareOp="GE"> 
              <ScalarOperator> 
              <Intrinsic FunctionName="datediff"> 
               <ScalarOperator> 
               <Const ConstValue="(4)" /> 
               </ScalarOperator> 
               <ScalarOperator> 
               <Convert DataType="datetimeoffset" Style="0" Implicit="true"> 
                <ScalarOperator> 
                <Identifier> 
                 <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="day_date" /> 
                </Identifier> 
                </ScalarOperator> 
               </Convert> 
               </ScalarOperator> 
               <ScalarOperator> 
               <Convert DataType="datetimeoffset" Style="0" Implicit="true"> 
                <ScalarOperator> 
                <Identifier> 
                 <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="first_status_day_date" /> 
                </Identifier> 
                </ScalarOperator> 
               </Convert> 
               </ScalarOperator> 
              </Intrinsic> 
              </ScalarOperator> 
              <ScalarOperator> 
              <Const ConstValue="(0)" /> 
              </ScalarOperator> 
             </Compare> 
             </ScalarOperator> 
             <ScalarOperator> 
             <Compare CompareOp="LE"> 
              <ScalarOperator> 
              <Intrinsic FunctionName="datediff"> 
               <ScalarOperator> 
               <Const ConstValue="(4)" /> 
               </ScalarOperator> 
               <ScalarOperator> 
               <Convert DataType="datetimeoffset" Style="0" Implicit="true"> 
                <ScalarOperator> 
                <Identifier> 
                 <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="day_date" /> 
                </Identifier> 
                </ScalarOperator> 
               </Convert> 
               </ScalarOperator> 
               <ScalarOperator> 
               <Convert DataType="datetimeoffset" Style="0" Implicit="true"> 
                <ScalarOperator> 
                <Identifier> 
                 <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="first_status_day_date" /> 
                </Identifier> 
                </ScalarOperator> 
               </Convert> 
               </ScalarOperator> 
              </Intrinsic> 
              </ScalarOperator> 
              <ScalarOperator> 
              <Const ConstValue="(14)" /> 
              </ScalarOperator> 
             </Compare> 
             </ScalarOperator> 
            </Logical> 
            </ScalarOperator> 
           </Predicate> 
           </IndexScan> 
          </RelOp> 
          </Top> 
         </RelOp> 
         </NestedLoops> 
        </RelOp> 
        </Parallelism> 
       </RelOp> 
       </ComputeScalar> 
      </RelOp> 
      </QueryPlan> 
     </StmtSimple> 
     </Statements> 
    </Batch> 
    </BatchSequence> 
</ShowPlanXML>

来源

2013-06-28 Oleksandr

你能不能给我们xml计划文件，以便我们看看那里真的发生了什么 – Surendra

你确定吗？他们是巨大的...有什么办法把他们放在一个紧凑的形式？ – Oleksandr

好吧，我添加了计划 – Oleksandr

此查询适用于这两种情况。

SELECT 
    a.id 
    ,(SELECT TOP 1 
      c.campaign_id 
     FROM [dwh].[dbo].[fact_customers_campaigns] c 
     WHERE 1 = 1 
      AND c.[customer_id] = a.[customer_id] 
      AND c.[day_date] >= DATEADD(dd, -14, a.[first_status_day_date]) 
      AND c.[day_date] <= a.[first_status_day_date] 
      ORDER BY c.[day_date] DESC, c.[time_of_day] DESC) 
FROM [dwh].[dbo].[dim_applications] a 
WHERE 1 = 1 
    AND a.[country_id] = 14

这个版本使用指标正常，并在这两种情况下记录的快速选择。

来源

2013-06-30 18:24:10 Oleksandr

从你的计划，我可以看到你有问题，统计的计划。例如：估计的行数（索引搜索）为1，但实际行数为139710. 您应该检查统计信息！

如果您正在从存储过程执行此查询，则应该使用RECOMPILE过程，因为sql cache中的计划（编译计划）不是“好”的一个第二个查询。

我不明白你的过滤条件1 = 1，为什么要使用它！

来源

2013-06-30 09:50:50 dixpac

统计信息是确定的并且是最新的，这是我询问之前检查的第一件事情。我直接从SSMS执行两个查询，所以不需要重新编译。关于1 = 1，我用它来轻松添加和/或评论更多的AND条件。这只是一种代码写作风格，实际上，这个问题并不重要。 – Oleksandr

SQL Server中，SELECT

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