实体框架使用 PatIndex 生成的查询不起作用
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【中文标题】实体框架使用 PatIndex 生成的查询不起作用【英文标题】：Query genereated by Entity Framework using PatIndex not working 【发布时间】：2013-05-30 12:22:27 【问题描述】：我有一个由 EF5 代码生成的查询，我在其中使用 SqlFunctions.PatIndex，该查询需要 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 运算符一样好用。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%'
这是两张表：
/****** 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
【问题讨论】：
使用慢查询创建一个工作负载，通过数据库引擎优化顾问运行它，然后查看它的建议。 这不是索引，我已经这样做了，like 运算符返回正常，但 patindex 没有。 您要搜索的字符串是什么？ 我正在搜索“13100%” 在这种情况下，使用LIKE 的查询将能够使用索引查找来查找值，而使用PATINDEX 的版本将使用索引扫描卡住。
【参考方案1】：
我怀疑“包含”搜索（例如：%3%00%）的两个查询的性能同样糟糕。但是，如果您的大部分搜索都包含前缀（例如：131%00%），您可以通过添加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：您也可以尝试更新您的统计信息。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 人员：估计7102，实际6858694从巨大的差异来看，我猜你已经关闭了 Auto Update Statistics 选项，并且你还没有安排一个作业来手动更新统计信息。
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。
UPDATE STATISTICS topic on MSDN
【讨论】：
patindex 相当糟糕，2:50 对 0:37。我读过的所有内容都表明 patindex 的性能应该更高，而不是更低。 @BlackICE：我不确定你在哪里读到PatIndex 会比Like 更好——如果有的话，我希望它会反过来。如果查看查询计划，您会发现Like 查询（带有前缀）能够读取Guarantor 表上的一小部分索引，而PatIndex 查询必须读取整件事。
@BlackICE：另外，尝试更新您的统计数据。我已经编辑了我的答案来解释。
***.com/questions/8052425/… blogs.msdn.com/b/deepakbi/archive/2012/07/25/…
我运行了更新统计信息，尽管我很确定我已经运行了它们，差别不大，但这可能是缓存，我得到的结果类似于运算符查询返回亚秒，patindex 返回〜5分钟。以上是关于实体框架使用 PatIndex 生成的查询不起作用的主要内容，如果未能解决你的问题，请参考以下文章
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