sql - 简单的自联接查询性能不佳

Question

任何人都可以就如何提高以下查询的性能提出建议。请注意，问题似乎是由where子句引起的。

数据（表包含大量行 - 500K+，调用它的参数集假定每个查询返回 2-5K 记录，目前需要 8-10 分钟）：

USE [SomeDb]
GO

    SET ANSI_NULLS ON
    GO

    SET QUOTED_IDENTIFIER ON
    GO

    CREATE TABLE [dbo].[Data](
        [x] [money] NOT NULL,
        [y] [money] NOT NULL,
     CONSTRAINT [PK_Data] PRIMARY KEY CLUSTERED 
    (
        [x] ASC
    )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    ) ON [PRIMARY]

    GO

查询

select top 10000
s.x as sx,
e.x as ex,
s.y as sy,
e.y as ey,
e.y - s.y as y_delta,
e.x - s.x as x_delta
from Data s 
    inner join Data e
    on e.x > s.x and e.x - s.x between xFrom and xTo
--where e.y - s.y > @yDelta -- when uncommented causes a huge delay

更新 1 - 执行计划

---

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<ShowPlanXML xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" Version="1.2" Build="11.0.2100.60" xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan">
  <BatchSequence>
    <Batch>
      <Statements>
        <StmtSimple StatementCompId="1" StatementEstRows="100" StatementId="1" StatementOptmLevel="FULL" StatementOptmEarlyAbortReason="GoodEnoughPlanFound" StatementSubTreeCost="0.0263655" StatementText="select top 100&#xD;&#xA;s.x as sx,&#xD;&#xA;e.x as ex,&#xD;&#xA;s.y as sy,&#xD;&#xA;e.y as ey,&#xD;&#xA;e.y - s.y as y_delta,&#xD;&#xA;e.x - s.x as x_delta&#xD;&#xA;from Data s &#xD;&#xA;    inner join Data e&#xD;&#xA; on e.x &gt; s.x and e.x - s.x between 100 and 105&#xD;&#xA;where e.y - s.y &gt; 0.01&#xD;&#xA;" StatementType="SELECT" QueryHash="0xAAAC02AC2D78CB56" QueryPlanHash="0x747994153CB2D637" 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="0" NonParallelPlanReason="NoParallelPlansInDesktopOrExpressEdition" CachedPlanSize="24" CompileTime="13" CompileCPU="13" CompileMemory="424">
            <MemoryGrantInfo SerialRequiredMemory="0" SerialDesiredMemory="0" />
            <OptimizerHardwareDependentProperties EstimatedAvailableMemoryGrant="52199" EstimatedPagesCached="14561" EstimatedAvailableDegreeOfParallelism="4" />
            <RelOp AvgRowSize="55" EstimateCPU="1E-05" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Compute Scalar" NodeId="0" Parallel="false" PhysicalOp="Compute Scalar" EstimatedTotalSubtreeCost="0.0263655">
              <OutputList>
                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                <ColumnReference Column="Expr1004" />
                <ColumnReference Column="Expr1005" />
              </OutputList>
              <ComputeScalar>
                <DefinedValues>
                  <DefinedValue>
                    <ColumnReference Column="Expr1004" />
                    <ScalarOperator ScalarString="[SomeDb].[dbo].[Data].[y] as [e].[y]-[SomeDb].[dbo].[Data].[y] as [s].[y]">
                      <Arithmetic Operation="SUB">
                        <ScalarOperator>
                          <Identifier>
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                          </Identifier>
                        </ScalarOperator>
                        <ScalarOperator>
                          <Identifier>
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                          </Identifier>
                        </ScalarOperator>
                      </Arithmetic>
                    </ScalarOperator>
                  </DefinedValue>
                  <DefinedValue>
                    <ColumnReference Column="Expr1005" />
                    <ScalarOperator ScalarString="[SomeDb].[dbo].[Data].[x] as [e].[x]-[SomeDb].[dbo].[Data].[x] as [s].[x]">
                      <Arithmetic Operation="SUB">
                        <ScalarOperator>
                          <Identifier>
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                          </Identifier>
                        </ScalarOperator>
                        <ScalarOperator>
                          <Identifier>
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                          </Identifier>
                        </ScalarOperator>
                      </Arithmetic>
                    </ScalarOperator>
                  </DefinedValue>
                </DefinedValues>
                <RelOp AvgRowSize="39" EstimateCPU="1E-05" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Top" NodeId="1" Parallel="false" PhysicalOp="Top" EstimatedTotalSubtreeCost="0.0263555">
                  <OutputList>
                    <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                    <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                    <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                    <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                  </OutputList>
                  <RunTimeInformation>
                    <RunTimeCountersPerThread Thread="0" ActualRows="100" ActualEndOfScans="1" ActualExecutions="1" />
                  </RunTimeInformation>
                  <Top RowCount="false" IsPercent="false" WithTies="false">
                    <TopExpression>
                      <ScalarOperator ScalarString="(100)">
                        <Const ConstValue="(100)" />
                      </ScalarOperator>
                    </TopExpression>
                    <RelOp AvgRowSize="39" EstimateCPU="151828" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Inner Join" NodeId="2" Parallel="false" PhysicalOp="Nested Loops" EstimatedTotalSubtreeCost="0.0263455">
                      <OutputList>
                        <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                        <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                        <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                        <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                      </OutputList>
                      <RunTimeInformation>
                        <RunTimeCountersPerThread Thread="0" ActualRows="100" ActualEndOfScans="0" ActualExecutions="1" />
                      </RunTimeInformation>
                      <NestedLoops Optimized="false">
                        <OuterReferences>
                          <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                          <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                        </OuterReferences>
                        <RelOp AvgRowSize="23" EstimateCPU="1.80448" EstimateIO="3.76461" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="1" LogicalOp="Clustered Index Scan" NodeId="3" Parallel="false" PhysicalOp="Clustered Index Scan" EstimatedTotalSubtreeCost="0.0032831" TableCardinality="1640290">
                          <OutputList>
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                          </OutputList>
                          <RunTimeInformation>
                            <RunTimeCountersPerThread Thread="0" ActualRows="15225" ActualEndOfScans="0" ActualExecutions="1" />
                          </RunTimeInformation>
                          <IndexScan Ordered="false" ForcedIndex="false" ForceScan="false" NoExpandHint="false">
                            <DefinedValues>
                              <DefinedValue>
                                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                              </DefinedValue>
                              <DefinedValue>
                                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                              </DefinedValue>
                            </DefinedValues>
                            <Object Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Index="[PK_Data]" Alias="[e]" IndexKind="Clustered" />
                          </IndexScan>
                        </RelOp>
                        <RelOp AvgRowSize="23" EstimateCPU="0.902317" EstimateIO="1.88387" EstimateRebinds="1" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Clustered Index Seek" NodeId="4" Parallel="false" PhysicalOp="Clustered Index Seek" EstimatedTotalSubtreeCost="0.0263655" TableCardinality="1640290">
                          <OutputList>
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                            <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                          </OutputList>
                          <RunTimeInformation>
                            <RunTimeCountersPerThread Thread="0" ActualRows="100" ActualEndOfScans="15224" ActualExecutions="15225" />
                          </RunTimeInformation>
                          <IndexScan Ordered="true" ScanDirection="FORWARD" ForcedIndex="false" ForceSeek="false" ForceScan="false" NoExpandHint="false" Storage="RowStore">
                            <DefinedValues>
                              <DefinedValue>
                                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                              </DefinedValue>
                              <DefinedValue>
                                <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                              </DefinedValue>
                            </DefinedValues>
                            <Object Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Index="[PK_Data]" Alias="[s]" IndexKind="Clustered" />
                            <SeekPredicates>
                              <SeekPredicateNew>
                                <SeekKeys>
                                  <EndRange ScanType="LT">
                                    <RangeColumns>
                                      <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                                    </RangeColumns>
                                    <RangeExpressions>
                                      <ScalarOperator ScalarString="[SomeDb].[dbo].[Data].[x] as [e].[x]">
                                        <Identifier>
                                          <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                                        </Identifier>
                                      </ScalarOperator>
                                    </RangeExpressions>
                                  </EndRange>
                                </SeekKeys>
                              </SeekPredicateNew>
                            </SeekPredicates>
                            <Predicate>
                              <ScalarOperator ScalarString="([SomeDb].[dbo].[Data].[x] as [e].[x]-[SomeDb].[dbo].[Data].[x] as [s].[x])&gt;=($100.0000) AND ([SomeDb].[dbo].[Data].[x] as [e].[x]-[SomeDb].[dbo].[Data].[x] as [s].[x])&lt;=($105.0000) AND ([SomeDb].[dbo].[Data].[y] as [e].[y]-[SomeDb].[dbo].[Data].[y] as [s].[y])&gt;(0.01)">
                                <Logical Operation="AND">
                                  <ScalarOperator>
                                    <Compare CompareOp="GE">
                                      <ScalarOperator>
                                        <Arithmetic Operation="SUB">
                                          <ScalarOperator>
                                            <Identifier>
                                              <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                                            </Identifier>
                                          </ScalarOperator>
                                          <ScalarOperator>
                                            <Identifier>
                                              <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                                            </Identifier>
                                          </ScalarOperator>
                                        </Arithmetic>
                                      </ScalarOperator>
                                      <ScalarOperator>
                                        <Const ConstValue="($100.0000)" />
                                      </ScalarOperator>
                                    </Compare>
                                  </ScalarOperator>
                                  <ScalarOperator>
                                    <Compare CompareOp="LE">
                                      <ScalarOperator>
                                        <Arithmetic Operation="SUB">
                                          <ScalarOperator>
                                            <Identifier>
                                              <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" />
                                            </Identifier>
                                          </ScalarOperator>
                                          <ScalarOperator>
                                            <Identifier>
                                              <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" />
                                            </Identifier>
                                          </ScalarOperator>
                                        </Arithmetic>
                                      </ScalarOperator>
                                      <ScalarOperator>
                                        <Const ConstValue="($105.0000)" />
                                      </ScalarOperator>
                                    </Compare>
                                  </ScalarOperator>
                                  <ScalarOperator>
                                    <Compare CompareOp="GT">
                                      <ScalarOperator>
                                        <Arithmetic Operation="SUB">
                                          <ScalarOperator>
                                            <Identifier>
                                              <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" />
                                            </Identifier>
                                          </ScalarOperator>
                                          <ScalarOperator>
                                            <Identifier>
                                              <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" />
                                            </Identifier>
                                          </ScalarOperator>
                                        </Arithmetic>
                                      </ScalarOperator>
                                      <ScalarOperator>
                                        <Const ConstValue="(0.01)" />
                                      </ScalarOperator>
                                    </Compare>
                                  </ScalarOperator>
                                </Logical>
                              </ScalarOperator>
                            </Predicate>
                          </IndexScan>
                        </RelOp>
                      </NestedLoops>
                    </RelOp>
                  </Top>
                </RelOp>
              </ComputeScalar>
            </RelOp>
          </QueryPlan>
        </StmtSimple>
      </Statements>
    </Batch>
  </BatchSequence>
</ShowPlanXML>

Answer 1

我经常看到通过将第一个查询的结果（在您的情况下没有 where 子句）插入到 TEMP 表或表变量中，然后从中选择（这基本上有助于查询优化器选择适当的执行）来获得巨大的性能提升计划）。

还刚刚注意到您在 Y 列上没有索引，这可能会加快一点速度。

编辑 另外，请尝试以下操作（给我带来更好的性能）：

SELECT * FROM 
    (SELECT
        s.x as sx,
        e.x as ex,
        s.y as sy,
        e.y as ey,
        e.y - s.y as y_delta,
        e.x - s.x as x_delta
    FROM Data s 
    JOIN Data e
    ON e.x > s.x 
) data
WHERE data.y_delta > @yDelta AND data.x_delta BETWEEN @xFrom AND @xTo

Answer 2

主要问题是 where 子句给出了一个交叉连接（不是我所说的简单连接）（给出许多行是连接比较 e 中的许多行与 s 中的一行）并且 .y 比较必须使用表扫描（如果不是整个表，至少是临时数据）。

如果查询很常见，则可以进行一次连接并将数据复制到预先计算的表中并对差异进行索引。

Answer 3

我能想到一个奇怪的策略来提高性能。这包括在表中添加一个自动递增的 id，然后根据 id 查找 Xfrom 和 Xto 的边界，然后查找该范围内的任何内容。

以下查询表明了我的意思：

with e1 as (
    select e.*,
           (select min(id) from data s where e.x between s.x + @xfrom and s.x + @xto) as idstart,
           (select max(id) from data s where e.x between s.x + @xfrom and s.x + @xto) as idend
    from data e
)
select <whatever>
from e1 join
     e1 s
     on e1.idstart = s.id
where e1.idstart <= e1.idend union all
select <whatever>
from e1 join
     e1 s
     on e1.idstart+1 = s.id
where e1.idstart+1 <= e1.idend
. . . 

我对返回下一个值的索引字段上的相关子查询很幸运。之后，连接是等连接，应该非常快。最后，您可能希望修改查询，以便它可以使用枚举值表进行比较。