entity-framework-5 - 实体框架使用 PatIndex 生成的查询不起作用

Question

我有一个由 EF5 代码生成的查询，我在其中使用 SqlFunctions.PatIndex 并且查询需要 5 分钟才能运行。如果我对 SQL 进行更改以使用 like 运算符，那么它会在亚秒内工作。从我读过的内容来看，PatIndex 应该至少与 like 运算符一样工作。这似乎是与 row_number() OVER 部分的一些交互，因为如果您只使用 patindex 子句执行最里面的选择，它也会在亚秒时间内返回。谁能告诉我为什么 row_number() OVER 正在杀死 PATINDEX 查询而不是使用 like 的查询？

这个有效：

exec sp_executesql N'SELECT TOP (10) 
[Project1].[C1] AS [C1], 
[Project1].[PersonId] AS [PersonId], 
[Project1].[FirstName] AS [FirstName], 
[Project1].[MiddleName] AS [MiddleName], 
[Project1].[LastName] AS [LastName], 
[Project1].[Suffix] AS [Suffix], 
[Project1].[DateOfBirth] AS [DateOfBirth], 
[Project1].[Ssn] AS [Ssn], 
[Project1].[CenterNumber] AS [CenterNumber], 
[Project1].[GuarantorNumber] AS [GuarantorNumber], 
[Project1].[GUNumber] AS [GUNumber], 
[Project1].[IndustrialClientNumber] AS [IndustrialClientNumber], 
[Project1].[Employer] AS [Employer]
FROM ( SELECT [Project1].[PersonId] AS [PersonId], [Project1].[CenterNumber] AS [CenterNumber], [Project1].[GuarantorNumber] AS [GuarantorNumber], [Project1].[GUNumber] AS [GUNumber], [Project1].[IndustrialClientNumber] AS [IndustrialClientNumber], [Project1].[Employer] AS [Employer], [Project1].[FirstName] AS [FirstName], [Project1].[MiddleName] AS [MiddleName], [Project1].[LastName] AS [LastName], [Project1].[Suffix] AS [Suffix], [Project1].[DateOfBirth] AS [DateOfBirth], [Project1].[Ssn] AS [Ssn], [Project1].[C1] AS [C1], row_number() OVER (ORDER BY [Project1].[FirstName] ASC) AS [row_number]
       FROM ( SELECT 
              [Extent1].[PersonId] AS [PersonId], 
              [Extent1].[CenterNumber] AS [CenterNumber], 
              [Extent1].[GuarantorNumber] AS [GuarantorNumber], 
              [Extent1].[GUNumber] AS [GUNumber], 
              [Extent1].[IndustrialClientNumber] AS [IndustrialClientNumber], 
              [Extent1].[Employer] AS [Employer], 
              [Extent2].[FirstName] AS [FirstName], 
              [Extent2].[MiddleName] AS [MiddleName], 
              [Extent2].[LastName] AS [LastName], 
              [Extent2].[Suffix] AS [Suffix], 
              [Extent2].[DateOfBirth] AS [DateOfBirth], 
              [Extent2].[Ssn] AS [Ssn], 
              ''0X0X'' AS [C1]
              FROM  [dbo].[vGuarantor] AS [Extent1]
              INNER JOIN [dbo].[vPerson] AS [Extent2] ON [Extent1].[PersonId] = [Extent2].[PersonId]
              WHERE ([Extent1].[CenterNumber] = @p__linq__0) AND ***([Extent1].[GuarantorNumber] like @p__linq__1)***
       )  AS [Project1]
)  AS [Project1]
WHERE [Project1].[row_number] > 0
ORDER BY [Project1].[FirstName] ASC
',N'@p__linq__0 nvarchar(4000),@p__linq__1 nvarchar(4000)',@p__linq__0=N'2',@p__linq__1=N'13100%'

这个没有：

exec sp_executesql N'SELECT TOP (10) 
[Project1].[C1] AS [C1], 
[Project1].[PersonId] AS [PersonId], 
[Project1].[FirstName] AS [FirstName], 
[Project1].[MiddleName] AS [MiddleName], 
[Project1].[LastName] AS [LastName], 
[Project1].[Suffix] AS [Suffix], 
[Project1].[DateOfBirth] AS [DateOfBirth], 
[Project1].[Ssn] AS [Ssn], 
[Project1].[CenterNumber] AS [CenterNumber], 
[Project1].[GuarantorNumber] AS [GuarantorNumber], 
[Project1].[GUNumber] AS [GUNumber], 
[Project1].[IndustrialClientNumber] AS [IndustrialClientNumber], 
[Project1].[Employer] AS [Employer]
FROM ( SELECT [Project1].[PersonId] AS [PersonId], [Project1].[CenterNumber] AS [CenterNumber], [Project1].[GuarantorNumber] AS [GuarantorNumber], [Project1].[GUNumber] AS [GUNumber], [Project1].[IndustrialClientNumber] AS [IndustrialClientNumber], [Project1].[Employer] AS [Employer], [Project1].[FirstName] AS [FirstName], [Project1].[MiddleName] AS [MiddleName], [Project1].[LastName] AS [LastName], [Project1].[Suffix] AS [Suffix], [Project1].[DateOfBirth] AS [DateOfBirth], [Project1].[Ssn] AS [Ssn], [Project1].[C1] AS [C1], row_number() OVER (ORDER BY [Project1].[FirstName] ASC) AS [row_number]
       FROM ( SELECT 
              [Extent1].[PersonId] AS [PersonId], 
              [Extent1].[CenterNumber] AS [CenterNumber], 
              [Extent1].[GuarantorNumber] AS [GuarantorNumber], 
              [Extent1].[GUNumber] AS [GUNumber], 
              [Extent1].[IndustrialClientNumber] AS [IndustrialClientNumber], 
              [Extent1].[Employer] AS [Employer], 
              [Extent2].[FirstName] AS [FirstName], 
              [Extent2].[MiddleName] AS [MiddleName], 
              [Extent2].[LastName] AS [LastName], 
              [Extent2].[Suffix] AS [Suffix], 
              [Extent2].[DateOfBirth] AS [DateOfBirth], 
              [Extent2].[Ssn] AS [Ssn], 
              ''0X0X'' AS [C1]
              FROM  [dbo].[vGuarantor] AS [Extent1]
              INNER JOIN [dbo].[vPerson] AS [Extent2] ON [Extent1].[PersonId] = [Extent2].[PersonId]
              WHERE ([Extent1].[CenterNumber] = @p__linq__0) AND ***(PATINDEX(@p__linq__1, [Extent1].[GuarantorNumber]) > 0)***
       )  AS [Project1]
)  AS [Project1]
WHERE [Project1].[row_number] > 0
ORDER BY [Project1].[FirstName] ASC
',N'@p__linq__0 nvarchar(4000),@p__linq__1 nvarchar(4000)',@p__linq__0=N'2',@p__linq__1=N'13100%'

下面是两张表：

/****** Object:  Table [Person]    Script Date: 5/30/2013 8:17:15 AM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [Person](
    [PersonId] [uniqueidentifier] NOT NULL,
    [FirstName] [nvarchar](255) NULL,
    [MiddleName] [nvarchar](255) NULL,
    [LastName] [nvarchar](255) NULL,
    [DateOfBirth] [datetime] NULL,
    [DateOfBirthIsGuess] [bit] NULL,
    [NickName] [nvarchar](255) NULL,
    [Suffix] [nchar](10) NULL,
    [Gender] [char](1) NULL,
    [SSN] [numeric](9, 0) NULL,
 CONSTRAINT [PK__Person__04E4BC85] PRIMARY KEY CLUSTERED 
(
    [PersonId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

/****** Object:  Index [PK__Person__04E4BC85]    Script Date: 7/18/2013 8:19:16 AM ******/
ALTER TABLE [PatientFirst].[Person] ADD  CONSTRAINT [PK__Person__04E4BC85] PRIMARY KEY CLUSTERED 
(
    [PersonId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
GO

/****** Object:  Index [IDX_Person.LastName]    Script Date: 7/18/2013 8:19:24 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Person.LastName] ON [PatientFirst].[Person]
(
    [LastName] ASC
)
INCLUDE (   [DateOfBirth],
    [FirstName],
    [MiddleName],
    [PersonId],
    [SSN],
    [Suffix]) 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

/****** Object:  Index [IDX_Person.FirstName]    Script Date: 7/18/2013 8:19:37 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Person.FirstName] ON [PatientFirst].[Person]
(
    [FirstName] ASC
)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

/****** Object:  Index [IDX_Person.DOB]    Script Date: 7/18/2013 8:19:47 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Person.DOB] ON [PatientFirst].[Person]
(
    [DateOfBirth] ASC
)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

/****** Object:  Table [Guarantor]    Script Date: 5/30/2013 8:17:11 AM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [Guarantor](
    [GuarantorId] [uniqueidentifier] NOT NULL,
    [CenterNumber] [nvarchar](10) NOT NULL,
    [GuarantorNumber] [nvarchar](10) NOT NULL,
    [IndustrialClientNumber] [int] NULL,
    [Employer] [varchar](4000) NULL,
    [ImportDate] [datetime] NULL,
    [GUNumber]  AS (([CenterNumber]+'*')+[GuarantorNumber]),
 CONSTRAINT [PK__Guarantor__44FF419A] PRIMARY KEY CLUSTERED 
(
    [GuarantorId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

ALTER TABLE [Guarantor] ADD  CONSTRAINT [DF__Guarantor__Guara__45F365D3]  DEFAULT (newid()) FOR [GuarantorId]
GO

ALTER TABLE [Guarantor] ADD  CONSTRAINT [DF_Guarantor_ImportDate]  DEFAULT (getdate()) FOR [ImportDate]
GO

ALTER TABLE [Guarantor]  WITH CHECK ADD  CONSTRAINT [FK_Guarantor_Person] FOREIGN KEY([GuarantorId])
REFERENCES [Person] ([PersonId])
GO

ALTER TABLE [Guarantor] CHECK CONSTRAINT [FK_Guarantor_Person]
GO
/****** Object:  Index [PK__Guarantor__44FF419A]    Script Date: 7/18/2013 8:17:43 AM ******/
ALTER TABLE [PatientFirst].[Guarantor] ADD  CONSTRAINT [PK__Guarantor__44FF419A] PRIMARY KEY CLUSTERED 
(
    [GuarantorId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
GO


/****** Object:  Index [IDX_Guarantor_CenterNumber]    Script Date: 7/18/2013 8:16:40 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Guarantor_CenterNumber] ON [PatientFirst].[Guarantor]
(
    [CenterNumber] ASC
)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


/****** Object:  Index [IDX_Guarantor_CenterNumberGuarantorNumber]    Script Date: 7/18/2013 8:16:45 AM ******/
CREATE UNIQUE NONCLUSTERED INDEX [IDX_Guarantor_CenterNumberGuarantorNumber] ON [PatientFirst].[Guarantor]
(
    [CenterNumber] ASC,
    [GuarantorNumber] 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, FILLFACTOR = 95) ON [PRIMARY]
GO


/****** Object:  Index [IDX_Guarantor_GuarantorNumber]    Script Date: 7/18/2013 8:17:01 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Guarantor_GuarantorNumber] ON [PatientFirst].[Guarantor]
(
    [GuarantorNumber] ASC
)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


/****** Object:  Index [IDX_Guarantor_GUNumber]    Script Date: 7/18/2013 8:17:09 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Guarantor_GUNumber] ON [PatientFirst].[Guarantor]
(
    [GUNumber] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
GO


/****** Object:  Index [IDX_Guarantor_ImportDate]    Script Date: 7/18/2013 8:17:21 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Guarantor_ImportDate] ON [PatientFirst].[Guarantor]
(
    [ImportDate] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
GO

/****** Object:  Index [IDX_Guarantor_IndustrialClientNumber]    Script Date: 7/18/2013 8:17:30 AM ******/
CREATE NONCLUSTERED INDEX [IDX_Guarantor_IndustrialClientNumber] ON [PatientFirst].[Guarantor]
(
    [IndustrialClientNumber] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 95) ON [PRIMARY]
GO

查询中使用的视图只是从基础表中选择 *。

like 算子的执行计划：

https://docs.google.com/file/d/0B4uS27e7ZMfCOTl5LS1UaHBSOTQ/edit?usp=sharing

Patindex 计划： https ://docs.google.com/file/d/0B4uS27e7ZMfCVTljNml4R0xjT28/edit?usp=sharing

score 0 · Accepted Answer

我怀疑“包含”搜索（例如：）的两个查询的性能%3%00%同样糟糕。但是，如果您的大多数搜索都包含前缀（例如：）131%00%，您可能可以通过添加StartsWith条件来提高性能。

例如：

var query = context.Guarantors.Where(g => g.CenterNumber == centerNumber);

int index = guarantorNumber.IndexOfAny(new[]{ '%', '_', '[' });
switch (index)
{
    case -1:
    {
        query = query.Where(g => g.GuarantorNumber == guarantorNumber);
        break;
    }
    case 0:
    {
        // Nothing we can do here. The query performance will suck.
        query = query.Where(g => SqlFunctions.PatIndex(guarantorNumber, g.GuarantorNumber) > 0);
        break;
    }
    default:
    {
        string prefix = guarantorNumber.Substring(0, index);
        query = query.Where(g => g.GuarantorNumber.StartsWith(prefix));
        if (index != guarantorNumber.Length - 1 || guarantorNumber[index] != '%')
        {
            query = query.Where(g => SqlFunctions.PatIndex(guarantorNumber, g.GuarantorNumber) > 0);
        }
        break;
    }
}

注意：您也可以尝试更新统计信息。执行计划显示两个表的估计行和实际行之间存在显着差异。

担保人：估计7188，实际107345
人：估计7102，实际6858694

从巨大的差异来看，我猜您已经Auto Update Statistics关闭了该选项，并且您还没有安排手动更新统计信息的工作。

尝试以下命令：

UPDATE STATISTICS Person;
UPDATE STATISTICS Guarantor;

这应该为 SQL 提供足够的信息来选择更明智的执行计划。

MSDN 上的 UPDATE STATISTICS 主题

entity-framework-5 - 实体框架使用 PatIndex 生成的查询不起作用

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