SQL Server, странное поведение SELECT,

У меня есть две таблицы: dim_applications со списком приложенийSQL Server, странное поведение 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

и журнал таблицу с сообщениями CRM, посланных клиентам:

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

То, что я хочу, чтобы выбрать является «campaign_id» ближайшей кампании для каждого приложения для конкретной страны. Эта кампания должна быть не «старше», чем 14 дней. Соединение двух таблиц выполняется с помощью «customer_id».

мой запрос на выборку, как это

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

он прекрасно работает, возвращает 1,5 миллиона записей в 7 секунд. Но когда я запускаю тот же запрос с country_id из последней страны в моем списке (14), тот же запрос становится очень медленным и может занять до 2 минут (1,2 миллиона записей). Почему такое различие? Планы одинаковы. Я просто не понимаю этого поведения. версии Серверные

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)

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)

Как я могу сделать время выполнения не зависит от выбранного county_id? Вот план COUNTRY_ID = 14, SQL Server 2012 с пакетом обновления 1

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    <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"> 
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       <OutputList> 
       <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
       <ColumnReference Column="Expr1006" /> 
       </OutputList> 
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        <ScalarOperator ScalarString="[dwh].[dbo].[fact_customers_campaigns].[campaign_id] as [c].[campaign_id]"> 
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        <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" /> 
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         <OutputList> 
         <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Alias="[a]" Column="id" /> 
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         </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> 
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          <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" /> 
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          </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> 
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           <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> 
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          <Object Database="[dwh]" Schema="[dbo]" Table="[dim_applications]" Index="[IX_dim_applications]" Alias="[a]" IndexKind="NonClustered" /> 
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             <Const ConstValue="(14)" /> 
             </ScalarOperator> 
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          <OutputList> 
          <ColumnReference Database="[dwh]" Schema="[dbo]" Table="[fact_customers_campaigns]" Alias="[c]" Column="campaign_id" /> 
          </OutputList> 
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           <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" /> 
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           <RunTimeCountersPerThread Thread="7" ActualRows="47272" Batches="0" ActualEndOfScans="211448" ActualExecutions="258720" ActualExecutionMode="Row" /> 
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           </RunTimeInformation> 
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            <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>

источник

2013-06-28 Oleksandr

Можете ли вы дать нам файл плана xml, чтобы мы могли посмотреть, что на самом деле происходит там – Surendra

Вы уверены? они огромные ... Есть ли способ положить их в какую-то компактную форму? – Oleksandr

Хорошо, я добавил план – Oleksandr

Этот запрос отлично подходит для обоих случаев.

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

Эта версия использует индексы правильно, и в обоих случаях записи выбираются быстро.

источник

2013-06-30 18:24:10 Oleksandr

Из вашего плана я могу видеть, что у вас есть проблемы со статистикой. Пример: Оценочное количество строк (поиск индекса) равно 1, но фактическое количество строк - 139710. Вы должны проверить свою статистику!

Если вы выполняете этот запрос из процедуры хранилища, вы должны выполнить процедуру RECOMPILE, потому что план в sql-кеше (скомпилированный план) не является «хорошим» передним вторым запросом.

Я не понимаю ваше состояние фильтра 1 = 1, зачем его использовать??

источник

2013-06-30 09:50:50 dixpac

статистика в порядке и актуальна, это было первое, что я проверил, прежде чем спрашивать. Я выполняю оба запроса непосредственно из SSMS, поэтому нет необходимости перекомпилировать. Что касается 1 = 1, я использую его, чтобы легко добавлять и/или комментировать другие условия И. Это всего лишь стиль написания кода, и на самом деле это не имеет значения для вопроса. – Oleksandr

SQL Server, странное поведение SELECT,

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