3

我在 LLBL 中有许多缓慢的预取查询。这是生成的 SQL 的简化版本：

SELECT DISTINCT 
    Column1
FROM 
    Table1
WHERE 
Table1.Table2ID IN 
(
    SELECT Table2.Table2ID AS Table2ID 
    FROM 
        Table2  
        INNER JOIN Table1 ON  Table2.Table2ID=Table1.Table2ID
        INNER JOIN 
        (
            SELECT DISTINCT 
                Table1.Table2ID AS Table2ID, 
                MAX(Table1.EffectiveDate) AS EffectiveDate 
            FROM Table1  
            WHERE Table1.EffectiveDate <= '2012-01-03 00:00:00:000'
            GROUP BY Table1.Table2ID
        ) MaxEffective  
        ON  
            MaxEffective.Table2ID = Table1.Table2ID 
            AND MaxEffective.EffectiveDate = Table1.EffectiveDate
)

我发现子查询执行得很快，如果我用实际结果替换那个子查询，外部查询很快。但是在一起，它们很慢。

我已经运行了 Database Engine Tuning Adviser，它有点帮助，但它仍然很慢。

我在理解执行计划方面不是很熟练，但似乎绝大多数时间都花在了 Table1 上的索引搜索上。

我希望它运行得更快，因为它是一个不相关的子查询。有什么我没看到的吗？

如果它只是直接的 SQL，我会重写查询并进行连接，但我几乎被 LLBL 困住了。有什么设置可以用来强制它加入吗？SQL Server 没有生成与连接相同的执行计划是有原因的吗？

编辑实际查询...

SELECT DISTINCT 
    ResidentialComponentValues.ResidentialComponentValueID AS ResidentialComponentValueId, 
    ResidentialComponentValues.ResidentialComponentTypeID AS ResidentialComponentTypeId, 
    ResidentialComponentValues.Value, 
    ResidentialComponentValues.Story, 
    ResidentialComponentValues.LastUpdated, 
    ResidentialComponentValues.LastUpdatedBy, 
    ResidentialComponentValues.ConcurrencyTimestamp, 
    ResidentialComponentValues.EffectiveDate, 
    ResidentialComponentValues.DefaultQuantity 
FROM 
ResidentialComponentValues  
WHERE 
ResidentialComponentValues.ResidentialComponentTypeID IN 
(
    SELECT ResidentialComponentTypes.ResidentialComponentTypeID AS ResidentialComponentTypeId 
    FROM 
        ResidentialComponentTypes  INNER JOIN ResidentialComponentValues  
        ON  ResidentialComponentTypes.ResidentialComponentTypeID=ResidentialComponentValues.ResidentialComponentTypeID
        INNER JOIN 
        (
            SELECT DISTINCT 
                ResidentialComponentValues.ResidentialComponentTypeID AS ResidentialComponentTypeId, 
                MAX(ResidentialComponentValues.EffectiveDate) AS EffectiveDate 
            FROM ResidentialComponentValues  
            WHERE ResidentialComponentValues.EffectiveDate <= '2012-01-03 00:00:00:000'
            GROUP BY ResidentialComponentValues.ResidentialComponentTypeID
        ) LPA_E1  
        ON  
            LPA_E1.ResidentialComponentTypeId = ResidentialComponentValues.ResidentialComponentTypeID 
            AND LPA_E1.EffectiveDate = ResidentialComponentValues.EffectiveDate
)

编辑创建语句：

/****** Object:  Table [dbo].[ResidentialComponentTypes]    Script Date: 01/03/2012 13:49:06 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[ResidentialComponentTypes](
    [ResidentialComponentTypeID] [int] IDENTITY(1,1) NOT NULL,
    [ComponentTypeName] [varchar](255) NOT NULL,
    [LastUpdated] [datetime] NOT NULL,
    [LastUpdatedBy] [varchar](50) NOT NULL,
    [ConcurrencyTimestamp] [timestamp] NOT NULL,
    [Active] [bit] NOT NULL,
 CONSTRAINT [PK_ResidentialComponentTypes] PRIMARY KEY CLUSTERED 
(
    [ResidentialComponentTypeID] 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
SET ANSI_PADDING OFF
GO
/****** Object:  Table [dbo].[ResidentialComponentValues]    Script Date: 01/03/2012 13:49:06 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[ResidentialComponentValues](
    [ResidentialComponentValueID] [int] IDENTITY(1,1) NOT NULL,
    [ResidentialComponentTypeID] [int] NOT NULL,
    [Value] [decimal](18, 3) NOT NULL,
    [Story] [varchar](255) NOT NULL,
    [LastUpdated] [datetime] NOT NULL,
    [LastUpdatedBy] [varchar](50) NOT NULL,
    [ConcurrencyTimestamp] [timestamp] NOT NULL,
    [EffectiveDate] [datetime] NOT NULL,
    [DefaultQuantity] [int] NOT NULL,
 CONSTRAINT [PK_ResidentialComponentPrices] PRIMARY KEY CLUSTERED 
(
    [ResidentialComponentValueID] 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
SET ANSI_PADDING OFF
GO
CREATE NONCLUSTERED INDEX [_dta_index_ResidentialComponentValues_71_56543435__K1] ON [dbo].[ResidentialComponentValues] 
(
    [ResidentialComponentValueID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [_dta_index_ResidentialComponentValues_71_56543435__K1_2_3_4_5_6_7_8_9] ON [dbo].[ResidentialComponentValues] 
(
    [ResidentialComponentValueID] ASC
)
INCLUDE ( [ResidentialComponentTypeID],
[Value],
[Story],
[LastUpdated],
[LastUpdatedBy],
[ConcurrencyTimestamp],
[EffectiveDate],
[DefaultQuantity]) WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [_dta_index_ResidentialComponentValues_71_56543435__K2_K1] ON [dbo].[ResidentialComponentValues] 
(
    [ResidentialComponentTypeID] ASC,
    [ResidentialComponentValueID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [_dta_index_ResidentialComponentValues_71_56543435__K2_K8_K1] ON [dbo].[ResidentialComponentValues] 
(
    [ResidentialComponentTypeID] ASC,
    [EffectiveDate] ASC,
    [ResidentialComponentValueID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [_dta_index_ResidentialComponentValues_71_56543435__K2_K8_K1_3_4_5_6_7_9] ON [dbo].[ResidentialComponentValues] 
(
    [ResidentialComponentTypeID] ASC,
    [EffectiveDate] ASC,
    [ResidentialComponentValueID] ASC
)
INCLUDE ( [Value],
[Story],
[LastUpdated],
[LastUpdatedBy],
[ConcurrencyTimestamp],
[DefaultQuantity]) WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
/****** Object:  ForeignKey [FK_ResidentialComponentValues_ResidentialComponentTypes]    Script Date: 01/03/2012 13:49:06 ******/
ALTER TABLE [dbo].[ResidentialComponentValues]  WITH CHECK ADD  CONSTRAINT [FK_ResidentialComponentValues_ResidentialComponentTypes] FOREIGN KEY([ResidentialComponentTypeID])
REFERENCES [dbo].[ResidentialComponentTypes] ([ResidentialComponentTypeID])
GO
ALTER TABLE [dbo].[ResidentialComponentValues] CHECK CONSTRAINT [FK_ResidentialComponentValues_ResidentialComponentTypes]
GO

在此处输入图像描述

4

2 回答 2

0

内部子查询不需要DISTINCT你已经GROUP BY ResidentialComponentTypeID：

    (
        SELECT DISTINCT 
            ResidentialComponentValues.ResidentialComponentTypeID 
              AS ResidentialComponentTypeId, 
            MAX(ResidentialComponentValues.EffectiveDate) 
              AS EffectiveDate 
        FROM ResidentialComponentValues 
        WHERE ResidentialComponentValues.EffectiveDate 
              <= '2012-01-03 00:00:00:000'
        GROUP BY ResidentialComponentValues.ResidentialComponentTypeID
    ) LPA_E1

不确定 SQL-Server 是否会识别这一点并进行优化，但您可以重写以确保：

    (
        SELECT 
            rcv.ResidentialComponentTypeID 
            MAX(rcv.EffectiveDate) AS EffectiveDate 
        FROM ResidentialComponentValues  AS rcv
        WHERE rcv.EffectiveDate 
              <= '2012-01-03 00:00:00:000'
        GROUP BY rcv.ResidentialComponentTypeID
    ) LPA_E1

如果我没记错的话，您也不需要DISTINCT查询中的另一个，也不需要额外的子查询嵌套。检查此重写是否给出相同的结果：

SELECT 
    v.ResidentialComponentValueID, 
    v.ResidentialComponentTypeID, 
    v.Value, 
    v.Story, 
    v.LastUpdated, 
    v.LastUpdatedBy, 
    v.ConcurrencyTimestamp, 
    v.EffectiveDate, 
    v.DefaultQuantity 
FROM 
        ResidentialComponentTypes  AS t
    INNER JOIN ResidentialComponentValues  AS v
        ON  t.ResidentialComponentTypeID=v.ResidentialComponentTypeID
    INNER JOIN 
        (
            SELECT 
                rcv.ResidentialComponentTypeID 
                MAX(rcv.EffectiveDate) AS EffectiveDate 
            FROM ResidentialComponentValues  AS rcv
            WHERE rcv.EffectiveDate 
                  <= '2012-01-03 00:00:00:000'
            GROUP BY rcv.ResidentialComponentTypeID
        ) LPA_E1 
        ON  
            LPA_E1.ResidentialComponentTypeId = v.ResidentialComponentTypeID 
            AND LPA_E1.EffectiveDate = v.EffectiveDate

您也不需要加入，ResidentialComponentTypes因为它有一个Foreign Key约束，ResidentialComponentValues但也许您有该加入可以在其他报告中使用。

不知道这将如何在 LLBL 中完成，但如果您可以DISTINCT从生成的代码中删除任何 - 尤其是第一个 - 或额外的嵌套（或额外的连接），它可能会帮助混淆的优化器。

于 2012-01-03T22:02:58.727 回答
0

从阅读您的查询中，我不清楚您实际想要实现的目标。您的外部查询是否试图为每个 ResidentialComponentType 仅选择最近有效的 ResidentialComponentValues 记录？

最DISTINCT里面的查询似乎没有必要，并且可能会导致数据库在优化查询时遇到一些困难。您只选择 2 列，并且按一列分组并聚合另一列，因此我确信结果已经不同。通过指定 ，您并没有帮助数据库更有效地执行此查询DISTINCT，尽管查询优化器可能会忽略它。

同样，第一个INNER JOIN对 ResidentialComponentValues 进行内部查询似乎是不必要的。

您的子查询中ON的第二个条件INNER JOIN（如下所示）让我感到困惑。看起来这只是将您的 LPA_E1 结果与INNER JOIN子查询中第一个的 ResidentialComponentValues 表连接起来，但我认为您真正想要做的是将它与外部查询中的 ResidentialComponentValues 表连接起来。

ON  
    LPA_E1.ResidentialComponentTypeId = ResidentialComponentValues.ResidentialComponentTypeID 
    AND LPA_E1.EffectiveDate = ResidentialComponentValues.EffectiveDate

我的猜测是，下面是您真正想要的查询，尽管我认为它不会产生与原始结果相同的结果。这只会为每个 ResidentialComponentType 选择最近有效的 ResidentialComponentValue 记录。

declare @endDate datetime
set @endDate = '2012-01-03 00:00:00:000'

SELECT
    ResidentialComponentValues.ResidentialComponentValueID AS ResidentialComponentValueId, 
    ResidentialComponentValues.ResidentialComponentTypeID AS ResidentialComponentTypeId, 
    ResidentialComponentValues.Value, 
    ResidentialComponentValues.Story, 
    ResidentialComponentValues.LastUpdated, 
    ResidentialComponentValues.LastUpdatedBy, 
    ResidentialComponentValues.ConcurrencyTimestamp, 
    ResidentialComponentValues.EffectiveDate, 
    ResidentialComponentValues.DefaultQuantity 
FROM 
    ResidentialComponentValues  
WHERE
    -- the effective date for this ResidentialComponentValue record has already passed
    ResidentialComponentValues.EffectiveDate <= @endDate
    -- and there does not exist any other ResidentialComponentValue record for the same ResidentialComponentType that is effective more recently
    and not exists (
        select 1
        from ResidentialComponentValues LPA_E1
        where
            LPA_E1.ResidentialComponentTypeID = ResidentialComponentValues.ResidentialComponentTypeID
            and LPA_E1.EffectiveDate <= @endDate
            and LPA_E1.EffectiveDate > ResidentialComponentValues.EffectiveDate
    )

旁注：我的猜测是，此查询将受益于 ResidentialComponentValues 表中列（ResidentialComponentTypeID、EffectiveDate）的 2 列索引。

此外，我认为下面显示的这个查询可能会产生与原始查询相同的结果，我猜它会执行得更快。

SELECT
    ResidentialComponentValues.ResidentialComponentValueID AS ResidentialComponentValueId, 
    ResidentialComponentValues.ResidentialComponentTypeID AS ResidentialComponentTypeId, 
    ResidentialComponentValues.Value, 
    ResidentialComponentValues.Story, 
    ResidentialComponentValues.LastUpdated, 
    ResidentialComponentValues.LastUpdatedBy, 
    ResidentialComponentValues.ConcurrencyTimestamp, 
    ResidentialComponentValues.EffectiveDate, 
    ResidentialComponentValues.DefaultQuantity 
FROM 
    ResidentialComponentValues  
WHERE
    -- show any ResidentialComponentValue records where there is any other currently effective ResidentialComponentValue record for the same ResidentialComponentType
    exists (
        select 1
        from ResidentialComponentValues LPA_E1
        where
            LPA_E1.ResidentialComponentTypeID = ResidentialComponentValues.ResidentialComponentTypeID
            and LPA_E1.EffectiveDate <= @endDate
    )

给定以下测试数据，第一个查询返回记录 2 和 4。第二个查询返回记录 1、2、3、4 和 5。

insert into ResidentialComponentTypes values (1)
insert into ResidentialComponentTypes values (2)
insert into ResidentialComponentTypes values (3)

insert into ResidentialComponentValues (ResidentialComponentValueID, ResidentialComponentTypeID, Value, Story, LastUpdated, LastUpdatedBy, EffectiveDate, DefaultQuantity)
          select 1, 1, 'One',   'Blah', getdate(), 'Blah', '2012-01-01', 1
union all select 2, 1, 'Two',   'Blah', getdate(), 'Blah', '2012-01-02', 1
union all select 3, 1, 'Three', 'Blah', getdate(), 'Blah', '2012-01-04', 1
union all select 4, 2, 'Four',  'Blah', getdate(), 'Blah', '2012-01-02', 1
union all select 5, 2, 'Five',  'Blah', getdate(), 'Blah', '2012-01-04', 1
union all select 6, 3, 'Six',   'Blah', getdate(), 'Blah', '2012-01-04', 1
于 2012-01-03T22:11:35.050 回答