Indice cluster non utilizzato in un'istruzione di eliminazione

Ho una tabella di SQL Server definita come segue

CREATE TABLE [dbo].[Production_Detail]
(
    [Id] [bigint] NOT NULL DEFAULT (NEXT VALUE FOR [dbo].[Production_Detail_Seq]),
    [Meta_Data_ID] INT NOT NULL , 
    [Production_Detail_Time] DATETIME NOT NULL,
    [Production_Detail_Time_Local] DATETIME NOT NULL,
    [Production_Detail_Value] FLOAT NULL,
    [IntegratedDM] BIT NOT NULL DEFAULT 0,
    [DailyIntegratedDM] BIT NOT NULL DEFAULT 0,
    [InsertedDate] DateTime NOT NULL,
    [ModifiedDate] DateTime NOT NULL,  

    CONSTRAINT [PK_Production_Detail] PRIMARY KEY ([Id]), 

    CONSTRAINT [UK_Production_Detail] UNIQUE ([Meta_Data_Id], [Production_Detail_Time]),

    CONSTRAINT [FK_Production_Detail_To_Meta_Data] FOREIGN KEY ([Meta_Data_ID]) REFERENCES [Meta_Data]([Meta_Data_ID]) 
)
GO

CREATE NONCLUSTERED INDEX [IX_Production_Detail_Production_Detail_Time_Local]
ON [dbo].[Production_Detail] ([Production_Detail_Time_Local])
INCLUDE ([Meta_Data_ID], [Production_Detail_Time], [Production_Detail_Value])
GO

CREATE UNIQUE NONCLUSTERED INDEX [IX_Production_Detail_Meta_Data_ID_Production_Detail_Time] 
ON [dbo].[Production_Detail] ([Meta_Data_ID] ASC, [Production_Detail_Time] ASC)
GO

CREATE NONCLUSTERED INDEX [IX_Production_Detail_IntegratedDM_MetaDataId]
ON [dbo].[Production_Detail] ([IntegratedDM], [Meta_Data_ID])
INCLUDE ([Production_Detail_Time])
GO

Questa tabella contiene dati in tempo reale, quindi i record vengono costantemente inseriti. Sto cercando di eliminare i dati più vecchi di 5 giorni. Ma quando l'eliminazione è in esecuzione, ho diverse istruzioni insert che generano deadlock.

Ecco la query di eliminazione. La #ToPurgetabella contiene l'ID che deve essere eliminato. La #ToPurgetabella non ha indici. Il numero di righe può variare, ma per il mio caso di test aveva oltre 3 milioni:

Declare @RowCount int;
set @RowCount = @@ROWCOUNT;

while @RowCount > 0
begin
    delete top(20000) pd
    from #ToPurge tp
    inner join [DataWarehouse].[dbo].[Production_Detail] pd on (tp.ID = pd.ID)

    set @RowCount = @@ROWCOUNT;
end

Ecco il piano di esecuzione dalla query di eliminazione

<?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="11.0.3128.0" xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan">
  <BatchSequence>
    <Batch>
      <Statements>
        <StmtSimple StatementCompId="1" StatementEstRows="20000" StatementId="1" StatementOptmLevel="FULL" StatementSubTreeCost="34.7996" StatementText="   delete top(20000) pd&#xD;&#xA;  from #ToPurge tp&#xD;&#xA;  inner join [DataWarehouse].[dbo].[Production_Detail] pd on (tp.ID = pd.ID)" StatementType="DELETE" QueryHash="0xF7A9CF8E140CDB4E" QueryPlanHash="0x2CC61A780737A398" RetrievedFromCache="false">
          <StatementSetOptions ANSI_NULLS="true" ANSI_PADDING="true" ANSI_WARNINGS="true" ARITHABORT="true" CONCAT_NULL_YIELDS_NULL="true" NUMERIC_ROUNDABORT="false" QUOTED_IDENTIFIER="true" />
          <QueryPlan CachedPlanSize="88" CompileTime="65" CompileCPU="65" CompileMemory="592">
            <ThreadStat Branches="2" />
            <MemoryGrantInfo SerialRequiredMemory="1024" SerialDesiredMemory="477448" />
            <OptimizerHardwareDependentProperties EstimatedAvailableMemoryGrant="209715" EstimatedPagesCached="419430" EstimatedAvailableDegreeOfParallelism="4" />
            <RelOp AvgRowSize="9" EstimateCPU="0.08" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Sequence" NodeId="0" Parallel="false" PhysicalOp="Sequence" EstimatedTotalSubtreeCost="34.7996">
              <OutputList />
              <Sequence>
                <RelOp AvgRowSize="9" EstimateCPU="0.02" EstimateIO="0.458155" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Delete" NodeId="1" Parallel="false" PhysicalOp="Index Delete" EstimatedTotalSubtreeCost="8.56272">
                  <OutputList />
                  <Update WithUnorderedPrefetch="true" DMLRequestSort="false">
                    <Object Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Index="[UK_Production_Detail]" Alias="[pd]" IndexKind="NonClustered" />
                    <RelOp AvgRowSize="36" EstimateCPU="0.00182568" EstimateIO="0.00328238" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Eager Spool" NodeId="3" Parallel="false" PhysicalOp="Table Spool" EstimatedTotalSubtreeCost="8.08456">
                      <OutputList>
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Meta_Data_ID" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time_Local" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="IntegratedDM" />
                      </OutputList>
                      <Spool>
                        <RelOp AvgRowSize="36" EstimateCPU="0.02" EstimateIO="1.31642" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Delete" NodeId="4" Parallel="false" PhysicalOp="Clustered Index Delete" EstimatedTotalSubtreeCost="32.3067">
                          <OutputList>
                            <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                            <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Meta_Data_ID" />
                            <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time" />
                            <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time_Local" />
                            <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="IntegratedDM" />
                          </OutputList>
                          <Update WithUnorderedPrefetch="true" DMLRequestSort="false">
                            <Object Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Index="[PK_Production_Detail]" Alias="[pd]" IndexKind="Clustered" />
                            <RelOp AvgRowSize="15" EstimateCPU="0.002" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Top" NodeId="6" Parallel="false" PhysicalOp="Top" EstimatedTotalSubtreeCost="30.9703">
                              <OutputList>
                                <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                              </OutputList>
                              <Top RowCount="false" IsPercent="false" WithTies="false">
                                <TopExpression>
                                  <ScalarOperator ScalarString="(20000)">
                                    <Const ConstValue="(20000)" />
                                  </ScalarOperator>
                                </TopExpression>
                                <RelOp AvgRowSize="15" EstimateCPU="0.0392491" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Gather Streams" NodeId="7" Parallel="true" PhysicalOp="Parallelism" EstimatedTotalSubtreeCost="30.9683">
                                  <OutputList>
                                    <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                  </OutputList>
                                  <Parallelism>
                                    <RelOp AvgRowSize="15" EstimateCPU="276.841" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Right Semi Join" NodeId="8" Parallel="true" PhysicalOp="Hash Match" EstimatedTotalSubtreeCost="30.929">
                                      <OutputList>
                                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                      </OutputList>
                                      <MemoryFractions Input="1" Output="1" />
                                      <Hash>
                                        <DefinedValues />
                                        <HashKeysBuild>
                                          <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                        </HashKeysBuild>
                                        <HashKeysProbe>
                                          <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                        </HashKeysProbe>
                                        <ProbeResidual>
                                          <ScalarOperator ScalarString="[DataWarehouse].[dbo].[Production_Detail].[Id] as [pd].[Id]=[tempdb].[dbo].[#ToPurge].[Id] as [tp].[Id]">
                                            <Compare CompareOp="EQ">
                                              <ScalarOperator>
                                                <Identifier>
                                                  <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                                </Identifier>
                                              </ScalarOperator>
                                              <ScalarOperator>
                                                <Identifier>
                                                  <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                                </Identifier>
                                              </ScalarOperator>
                                            </Compare>
                                          </ScalarOperator>
                                        </ProbeResidual>
                                        <RelOp AvgRowSize="15" EstimateCPU="2.83429" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="3910180" LogicalOp="Bitmap Create" NodeId="9" Parallel="true" PhysicalOp="Bitmap" EstimatedTotalSubtreeCost="9.99726">
                                          <OutputList>
                                            <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                          </OutputList>
                                          <Bitmap>
                                            <DefinedValues>
                                              <DefinedValue>
                                                <ColumnReference Column="Bitmap1007" />
                                              </DefinedValue>
                                            </DefinedValues>
                                            <HashKeys>
                                              <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                            </HashKeys>
                                            <RelOp AvgRowSize="15" EstimateCPU="2.83429" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="3910180" LogicalOp="Repartition Streams" NodeId="10" Parallel="true" PhysicalOp="Parallelism" EstimatedTotalSubtreeCost="9.99726">
                                              <OutputList>
                                                <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                              </OutputList>
                                              <Parallelism PartitioningType="Hash">
                                                <PartitionColumns>
                                                  <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                                </PartitionColumns>
                                                <RelOp AvgRowSize="15" EstimateCPU="1.07532" EstimateIO="6.08765" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="3910180" LogicalOp="Table Scan" NodeId="11" Parallel="true" PhysicalOp="Table Scan" EstimatedTotalSubtreeCost="7.16297" TableCardinality="3910180">
                                                  <OutputList>
                                                    <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                                  </OutputList>
                                                  <TableScan Ordered="false" ForcedIndex="false" ForceScan="false" NoExpandHint="false">
                                                    <DefinedValues>
                                                      <DefinedValue>
                                                        <ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" Column="Id" />
                                                      </DefinedValue>
                                                    </DefinedValues>
                                                    <Object Database="[tempdb]" Schema="[dbo]" Table="[#ToPurge]" Alias="[tp]" IndexKind="Heap" />
                                                  </TableScan>
                                                </RelOp>
                                              </Parallelism>
                                            </RelOp>
                                          </Bitmap>
                                        </RelOp>
                                        <RelOp AvgRowSize="15" EstimateCPU="0.675882" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="902193" LogicalOp="Repartition Streams" NodeId="12" Parallel="true" PhysicalOp="Parallelism" EstimatedTotalSubtreeCost="3.17684">
                                          <OutputList>
                                            <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                          </OutputList>
                                          <Parallelism PartitioningType="Hash">
                                            <PartitionColumns>
                                              <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                            </PartitionColumns>
                                            <RelOp AvgRowSize="15" EstimateCPU="43.216" EstimateIO="391.867" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="902193" LogicalOp="Index Scan" NodeId="13" Parallel="true" PhysicalOp="Index Scan" EstimatedTotalSubtreeCost="2.50096" TableCardinality="157149000">
                                              <OutputList>
                                                <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                              </OutputList>
                                              <IndexScan Ordered="true" ScanDirection="FORWARD" ForcedIndex="false" ForceSeek="false" ForceScan="false" NoExpandHint="false" Storage="RowStore">
                                                <DefinedValues>
                                                  <DefinedValue>
                                                    <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                                  </DefinedValue>
                                                </DefinedValues>
                                                <Object Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Index="[UK_Production_Detail]" Alias="[pd]" IndexKind="NonClustered" />
                                                <Predicate>
                                                  <ScalarOperator ScalarString="PROBE([Bitmap1007],[DataWarehouse].[dbo].[Production_Detail].[Id] as [pd].[Id],N'[IN ROW]')">
                                                    <Intrinsic FunctionName="PROBE">
                                                      <ScalarOperator>
                                                        <Identifier>
                                                          <ColumnReference Column="Bitmap1007" />
                                                        </Identifier>
                                                      </ScalarOperator>
                                                      <ScalarOperator>
                                                        <Identifier>
                                                          <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                                                        </Identifier>
                                                      </ScalarOperator>
                                                      <ScalarOperator>
                                                        <Const ConstValue="N'[IN ROW]'" />
                                                      </ScalarOperator>
                                                    </Intrinsic>
                                                  </ScalarOperator>
                                                </Predicate>
                                              </IndexScan>
                                            </RelOp>
                                          </Parallelism>
                                        </RelOp>
                                      </Hash>
                                    </RelOp>
                                  </Parallelism>
                                </RelOp>
                              </Top>
                            </RelOp>
                          </Update>
                        </RelOp>
                      </Spool>
                    </RelOp>
                  </Update>
                </RelOp>
                <RelOp AvgRowSize="9" EstimateCPU="0.02" EstimateIO="0.906841" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Delete" NodeId="16" Parallel="false" PhysicalOp="Index Delete" EstimatedTotalSubtreeCost="9.0114">
                  <OutputList />
                  <Update WithUnorderedPrefetch="true" DMLRequestSort="false">
                    <Object Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Index="[IX_Production_Detail_Production_Detail_Time_Local]" Alias="[pd]" IndexKind="NonClustered" />
                    <RelOp AvgRowSize="36" EstimateCPU="0.00182568" EstimateIO="0.00328238" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Eager Spool" NodeId="18" Parallel="false" PhysicalOp="Table Spool" EstimatedTotalSubtreeCost="8.08456">
                      <OutputList>
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Meta_Data_ID" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time_Local" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="IntegratedDM" />
                      </OutputList>
                      <Spool PrimaryNodeId="3" />
                    </RelOp>
                  </Update>
                </RelOp>
                <RelOp AvgRowSize="9" EstimateCPU="0.02" EstimateIO="0.458164" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Delete" NodeId="19" Parallel="false" PhysicalOp="Index Delete" EstimatedTotalSubtreeCost="8.56272">
                  <OutputList />
                  <Update WithUnorderedPrefetch="true" DMLRequestSort="false">
                    <Object Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Index="[IX_Production_Detail_Meta_Data_ID_Production_Detail_Time]" Alias="[pd]" IndexKind="NonClustered" />
                    <RelOp AvgRowSize="36" EstimateCPU="0.00182568" EstimateIO="0.00328238" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Eager Spool" NodeId="21" Parallel="false" PhysicalOp="Table Spool" EstimatedTotalSubtreeCost="8.08456">
                      <OutputList>
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Meta_Data_ID" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time_Local" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="IntegratedDM" />
                      </OutputList>
                      <Spool PrimaryNodeId="3" />
                    </RelOp>
                  </Update>
                </RelOp>
                <RelOp AvgRowSize="9" EstimateCPU="0.02" EstimateIO="0.478182" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Delete" NodeId="22" Parallel="false" PhysicalOp="Index Delete" EstimatedTotalSubtreeCost="8.58274">
                  <OutputList />
                  <Update WithUnorderedPrefetch="true" DMLRequestSort="false">
                    <Object Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Index="[IX_Production_Detail_IntegratedDM_MetaDataId]" Alias="[pd]" IndexKind="NonClustered" />
                    <RelOp AvgRowSize="36" EstimateCPU="0.00182568" EstimateIO="0.00328238" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="20000" LogicalOp="Eager Spool" NodeId="24" Parallel="false" PhysicalOp="Table Spool" EstimatedTotalSubtreeCost="8.08456">
                      <OutputList>
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Id" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Meta_Data_ID" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="Production_Detail_Time_Local" />
                        <ColumnReference Database="[DataWarehouse]" Schema="[dbo]" Table="[Production_Detail]" Alias="[pd]" Column="IntegratedDM" />
                      </OutputList>
                      <Spool PrimaryNodeId="3" />
                    </RelOp>
                  </Update>
                </RelOp>
              </Sequence>
            </RelOp>
          </QueryPlan>
        </StmtSimple>
      </Statements>
    </Batch>
  </BatchSequence>
</ShowPlanXML>

Come puoi vedere nel piano di esecuzione, l'ottimizzatore non utilizza l'indice cluster del primario, ma utilizza invece la chiave univoca che non contiene il campo Id. Penso che questo sia il motivo per cui ho deadlock poiché ha bisogno di bloccare più pagine che se stesse usando l'indice giusto.

Provo ad aggiungere un indice non cluster con l'ID e successivamente l'ottimizzatore lo sta usando.

CREATE UNIQUE NONCLUSTERED INDEX [NonClusteredIndex-20160617-104555] 
ON [dbo].[Production_Detail] ([Id] ASC)    
GO

Vorrei sapere perché l'ottimizzatore non utilizza l'indice cluster, ma utilizza quello non cluster?

Vorrei sapere perché l'ottimizzatore non utilizza l'indice cluster, ma utilizza quello non cluster?

Questa sarà una decisione dell'ottimizzatore basato sui costi. Stima che è più economico scansionare completamente l'indice ristretto.

Sembra che ti aspettavi un loop nidificato con ricerche sull'indice cluster?

Il piano di esecuzione mostra che la tabella #ToPurgeha 3,9 milioni di righe.

Ci vorranno 195 lotti per cancellare. Supponendo che tutte le righe in #ToPurgesiano univoche e esistano inizialmente in Production_Detaile che l'output delle righe #ToPurgesia in un ordine coerente per ciascun batch (sto ignorando il parallelismo), allora ogni batch successivo finirà per cercare tutte le righe che sono già state eliminate in precedenza i batch prima di arrivare finalmente a una patch di righe che non sono ancora state elaborate, in totale il deleteprocesso farà più di un terzo di un miliardo di indici alla ricerca di righe già eliminate .

0 + 20,000 + 40,000 + ... + 3,880,000 = 378,300,000

Questa non è la logica utilizzata dall'ottimizzatore basato sui costi (che comporterà istogrammi delle due tabelle e un rowgoal per il TOP 20000) ma mostra comunque che questa non è una buona strategia.

Potresti provare quanto segue per limitare il numero di ricerche a 20.000 per iterazione e vedere se ora ottieni il piano desiderato.

CREATE TABLE #ToPurge
  (
     [BatchId] [INT] NULL,
     [Id]      [BIGINT] NOT NULL,
     UNIQUE CLUSTERED([BatchId], [Id])
  );

/*Your insert statement to #ToPurge here*/

WITH CTE
     AS (SELECT *,
                1 + ( ROW_NUMBER() OVER (ORDER BY Id) / 20000 ) AS _BatchId
         FROM   #ToPurge)
UPDATE CTE
SET    [BatchId] = [_BatchId];

DECLARE @BatchCounter INT = 1;

WHILE @BatchCounter <= (SELECT MAX([BatchId])
                        FROM   #ToPurge)
  BEGIN
      DELETE pd
      FROM   #ToPurge tp
             INNER JOIN [DataWarehouse].[dbo].[Production_Detail] pd
               ON ( tp.ID = pd.ID )
      WHERE  tp.BatchId = @BatchCounter

      SET @BatchCounter+=1;
  END