sp_create_plan_guide (Transact-SQL)

Straipsnis
07/08/2024

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

Creates a plan guide for associating query hints or actual query plans with queries in a database. For more information about plan guides, see Plan Guides.

Transact-SQL syntax conventions

Syntax

sp_create_plan_guide
    [ @name = ] N'name'
    [ , [ @stmt = ] N'stmt' ]
    , [ @type = ] { N'OBJECT' | N'SQL' | N'TEMPLATE' }
    [ , [ @module_or_batch = ] { N' [ schema_name. ] object_name' | N'batch_text' } ]
    [ , [ @params = ] N'@parameter_name data_type [ ,... n ]' ]
    [ , [ @hints = ] { N'OPTION ( query_hint [ , ...n ] )' | N'XML_showplan' } ]
[ ; ]

Arguments

[ @name = ] N'name'

The name of the plan guide. @name is sysname, with no default, and a maximum length of 124 characters. Plan guide names are scoped to the current database. @name must comply with the rules for identifiers and can't start with the number sign (#).

[ @stmt = ] N'stmt'

A Transact-SQL statement against which to create a plan guide. @stmt is nvarchar(max), with a default of NULL. When the SQL Server query optimizer recognizes a query that matches @stmt, @name takes effect. For the creation of a plan guide to succeed, @stmt must appear in the context specified by the @type, @module_or_batch, and @params parameters.

@stmt must be provided in a way that allows for the query optimizer to match it with the corresponding statement, supplied within the batch or module identified by @module_or_batch and @params. For more information, see the Remarks section. The size of @stmt is limited only by available memory of the server.

[ @type = ] { N'OBJECT' | N'SQL' | N'TEMPLATE' }

The type of entity in which @stmt appears. This specifies the context for matching @stmt to @name. @type is nvarchar(60), and can be one of these values:

OBJECT

Indicates @stmt appears in the context of a Transact-SQL stored procedure, scalar function, multistatement table-valued function, or Transact-SQL DML trigger in the current database.
SQL

Indicates @stmt appears in the context of a stand-alone statement or batch that can be submitted to SQL Server through any mechanism. Transact-SQL statements submitted by common language runtime (CLR) objects or extended stored procedures, or by using EXEC N'<sql_string>', are processed as batches on the server and, therefore, should be identified as @type of SQL. If SQL is specified, the query hint PARAMETERIZATION { FORCED | SIMPLE } can't be specified in the @hints parameter.
TEMPLATE

Indicates the plan guide applies to any query that parameterizes to the form indicated in @stmt. If TEMPLATE is specified, only the PARAMETERIZATION { FORCED | SIMPLE } query hint can be specified in the @hints parameter. For more information about TEMPLATE plan guides, see Specify Query Parameterization Behavior by Using Plan Guides.

[ @module_or_batch = ] { N' [ schema_name. ] object_name' | N'batch_text' }

Specifies either the name of the object in which @stmt appears, or the batch text in which @stmt appears. @module_or_batch is nvarchar(max), with a default of NULL. The batch text can't include a USE <database> statement.

For a plan guide to match a batch submitted from an application, @module_or_batch must be provided in the same format, character-for-character, as it's submitted to SQL Server. No internal conversion is performed to facilitate this match. For more information, see the Remarks section.

[ <schema_name>. ] <object_name> specifies the name of a Transact-SQL stored procedure, scalar function, multistatement table-valued function, or Transact-SQL DML trigger that contains @stmt. If <schema_name> isn't specified, <schema_name> uses the schema of the current user. If NULL is specified and @type is SQL, the value of @module_or_batch is set to the value of @stmt. If @type is TEMPLATE, @module_or_batch must be NULL.

[ @params = ] N'@parameter_name data_type [ ,... n ]'

Specifies the definitions of all parameters that are embedded in @stmt. @params is nvarchar(max), with a default of NULL. @params applies only when either of the following options is true:

@type is SQL or TEMPLATE. If TEMPLATE, @params must not be NULL.
@stmt is submitted by using sp_executesql and a value for the @params parameter is specified, or SQL Server internally submits a statement after parameterizing it. Submission of parameterized queries from database APIs (including ODBC, OLE DB, and ADO.NET) appears to SQL Server as calls to sp_executesql or to API server cursor routines; therefore, they can also be matched by SQL or TEMPLATE plan guides.

@params must be supplied in the exact same format as it's submitted to SQL Server either by using sp_executesql or submitted internally after parameterization. For more information, see the Remarks section. If the batch doesn't contain parameters, NULL must be specified. The size of @params is limited only by available server memory.

[ @hints = ] { N'OPTION ( query_hint [ , ...n ] )' | N'XML_showplan' }

@hints is nvarchar(max), with a default of NULL.

OPTION ( <query_hint> [ , ...n ] )

Specifies an OPTION clause to attach to a query that matches @stmt. @hints must be syntactically the same as an OPTION clause in a SELECT statement, and can contain any valid sequence of query hints.
<XML_showplan>'

The query plan in XML format to be applied as a hint.

We recommend assigning the XML showplan to a variable. Otherwise, you must escape any single quotation marks in the showplan by preceding them with another single quotation mark. See example E.
NULL

Indicates that any existing hint specified in the OPTION clause of the query isn't applied to the query. For more information, see OPTION clause.

Remarks

The arguments to sp_create_plan_guide must be provided in the order that is shown. When you supply values for the parameters of sp_create_plan_guide, all parameter names must be specified explicitly, or none at all. For example, if @name = is specified, then @stmt =, @type =, and so on, must also be specified. Likewise, if @name = is omitted and only the parameter value is provided, the remaining parameter names must also be omitted, and only their values provided. Argument names are for descriptive purposes only, to help understand the syntax. SQL Server doesn't verify that the specified parameter name matches the name for the parameter in the position where the name is used.

You can create more than one OBJECT or SQL plan guide for the same query and batch or module. However, only one plan guide can be enabled at any given time.

Plan guides of type OBJECT can't be created for an @module_or_batch value that references a stored procedure, function, or DML trigger that specifies the WITH ENCRYPTION clause or that is temporary.

Trying to drop or modify a function, stored procedure, or DML trigger that is referenced by a plan guide, either enabled or disabled, causes an error. Trying to drop a table that's a trigger defined on it that is referenced by a plan guide also causes an error.

Plan guides can't be used in every edition of SQL Server. For a list of features that are supported by the editions of SQL Server, see Editions and supported features of SQL Server 2022. Plan guides are visible in any edition. You can also attach a database that contains plan guides to any edition. Plan guides remain intact when you restore or attach a database to an upgraded version of SQL Server. You should verify the desirability of the plan guides in each database after performing a server upgrade.

Plan guide matching requirements

For plan guides that specify @type of SQL or TEMPLATE to successfully match a query, the values for @module_or_batch and @params [, ...n ] must be provided in exactly the same format as their counterparts submitted by the application. This means you must provide the batch text exactly as the SQL Server compiler receives it. To capture the actual batch and parameter text, you can use SQL Server Profiler. For more information, see Use SQL Server Profiler to create and test plan guides.

When @type is SQL and @module_or_batch is set to NULL, the value of @module_or_batch is set to the value of @stmt. This means that the value for @stmt must be provided in exactly the same format, character-for-character, as it's submitted to SQL Server. No internal conversion is performed to facilitate this match.

When SQL Server matches the value of @stmt to @module_or_batch and @params [, ...n ], or if @type is OBJECT, to the text of the corresponding query inside <object_name>, the following string elements aren't considered:

White space characters (tabs, spaces, carriage returns, or line feeds) inside the string
Comments (-- or /* */)
Trailing semicolons

For example, SQL Server can match the @stmt string N'SELECT * FROM T WHERE a = 10' to the following @module_or_batch:

 N'SELECT *
 FROM T
 WHERE a = 10'

However, the same string wouldn't be matched to this @module_or_batch:

N'SELECT * FROM T WHERE b = 10'

SQL Server ignores the carriage return, line feed, and space characters inside the first query. In the second query, the sequence WHERE b = 10 is interpreted differently from WHERE a = 10. Matching is case-sensitive and accent-sensitive (even when the collation of the database is case-insensitive), except if there are keywords, where case is insensitive. Matching is sensitive to blank spaces. Matching is insensitive to shortened forms of keywords. For example, the keywords EXECUTE, EXEC, and execute are considered equivalent.

Plan guide effect on the plan cache

Creating a plan guide on a module removes the query plan for that module from the plan cache. Creating a plan guide of type OBJECT or SQL on a batch removes the query plan for a batch that's the same hash value. Creating a plan guide of type TEMPLATE removes all single-statement batches from the plan cache within that database.

Permissions

To create a plan guide of type OBJECT, requires ALTER permission on the referenced object. To create a plan guide of type SQL or TEMPLATE, requires ALTER permission on the current database.

Examples

A. Create a plan guide of type OBJECT for a query in a stored procedure

The following example creates a plan guide that matches a query executed in the context of an application-based stored procedure, and applies the OPTIMIZE FOR hint to the query.

Here's the stored procedure:

IF OBJECT_ID(N'Sales.GetSalesOrderByCountry', N'P') IS NOT NULL
    DROP PROCEDURE Sales.GetSalesOrderByCountry;
GO

CREATE PROCEDURE Sales.GetSalesOrderByCountry (
    @Country_region NVARCHAR(60)
)
AS
BEGIN
    SELECT *
    FROM Sales.SalesOrderHeader AS h
    INNER JOIN Sales.Customer AS c
        ON h.CustomerID = c.CustomerID
    INNER JOIN Sales.SalesTerritory AS t
        ON c.TerritoryID = t.TerritoryID
    WHERE t.CountryRegionCode = @Country_region;
END
GO

Here's the plan guide created on the query in the stored procedure:

EXEC sp_create_plan_guide
    @name = N'Guide1',
    @stmt = N'SELECT *
              FROM Sales.SalesOrderHeader AS h
              INNER JOIN Sales.Customer AS c
                 ON h.CustomerID = c.CustomerID
              INNER JOIN Sales.SalesTerritory AS t
                 ON c.TerritoryID = t.TerritoryID
              WHERE t.CountryRegionCode = @Country_region',
    @type = N'OBJECT',
    @module_or_batch = N'Sales.GetSalesOrderByCountry',
    @params = NULL,
    @hints = N'OPTION (OPTIMIZE FOR (@Country_region = N''US''))';

B. Create a plan guide of type SQL for a stand-alone query

The following example creates a plan guide to match a query in a batch submitted by an application that uses the sp_executesql system stored procedure.

Here's the batch:

SELECT TOP 1 *
FROM Sales.SalesOrderHeader
ORDER BY OrderDate DESC;

To prevent a parallel execution plan from being generated on this query, create the following plan guide:

EXEC sp_create_plan_guide
    @name = N'Guide1',
    @stmt = N'SELECT TOP 1 *
              FROM Sales.SalesOrderHeader
              ORDER BY OrderDate DESC',
    @type = N'SQL',
    @module_or_batch = NULL,
    @params = NULL,
    @hints = N'OPTION (MAXDOP 1)';

C. Create a plan guide of type TEMPLATE for the parameterized form of a query

The following example creates a plan guide that matches any query that parameterizes to a specified form, and directs SQL Server to force parameterization of the query. The following two queries are syntactically equivalent, but differ only in their constant literal values.

SELECT *
FROM AdventureWorks2022.Sales.SalesOrderHeader AS h
INNER JOIN AdventureWorks2022.Sales.SalesOrderDetail AS d
    ON h.SalesOrderID = d.SalesOrderID
WHERE h.SalesOrderID = 45639;

SELECT *
FROM AdventureWorks2022.Sales.SalesOrderHeader AS h
INNER JOIN AdventureWorks2022.Sales.SalesOrderDetail AS d
    ON h.SalesOrderID = d.SalesOrderID
WHERE h.SalesOrderID = 45640;

Here's the plan guide on the parameterized form of the query:

EXEC sp_create_plan_guide
    @name = N'TemplateGuide1',
    @stmt = N'SELECT * FROM AdventureWorks2022.Sales.SalesOrderHeader AS h
              INNER JOIN AdventureWorks2022.Sales.SalesOrderDetail AS d
                  ON h.SalesOrderID = d.SalesOrderID
              WHERE h.SalesOrderID = @0',
    @type = N'TEMPLATE',
    @module_or_batch = NULL,
    @params = N'@0 int',
    @hints = N'OPTION(PARAMETERIZATION FORCED)';

In the previous example, the value for the @stmt parameter is the parameterized form of the query. The only reliable way to obtain this value for use in sp_create_plan_guide is to use the sp_get_query_template system stored procedure. The following script obtains the parameterized query and then creates a plan guide on it.

DECLARE @stmt NVARCHAR(MAX);
DECLARE @params NVARCHAR(MAX);

EXEC sp_get_query_template N'SELECT * FROM AdventureWorks2022.Sales.SalesOrderHeader AS h
      INNER JOIN AdventureWorks2022.Sales.SalesOrderDetail AS d
          ON h.SalesOrderID = d.SalesOrderID
      WHERE h.SalesOrderID = 45639;',
    @stmt OUTPUT,
    @params OUTPUT

EXEC sp_create_plan_guide N'TemplateGuide1',
    @stmt,
    N'TEMPLATE',
    NULL,
    @params,
    N'OPTION(PARAMETERIZATION FORCED)';

Important

The value of the constant literals in the @stmt parameter passed to sp_get_query_template might affect the data type that is chosen for the parameter that replaces the literal. This will affect plan guide matching. You might have to create more than one plan guide to handle different parameter value ranges.

D. Create a plan guide on a query submitted by using an API cursor request

Plan guides can match queries that are submitted from API server cursor routines. These routines include sp_cursorprepare, sp_cursorprepexec, and sp_cursoropen. Applications that use the ADO, OLE DB, and ODBC APIs frequently interact with SQL Server by using API server cursors. You can see the invocation of API server cursor routines in SQL Server Profiler traces by viewing the RPC:Starting profiler trace event.

Suppose the following data appears in an RPC:Starting profiler trace event for a query you want to tune with a plan guide:

DECLARE @p1 INT;
SET @p1 = - 1;

DECLARE @p2 INT;
SET @p2 = 0;

DECLARE @p5 INT;
SET @p5 = 4104;

DECLARE @p6 INT;
SET @p6 = 8193;

DECLARE @p7 INT;
SET @p7 = 0;

EXEC sp_cursorprepexec @p1 OUTPUT,
    @p2 OUTPUT,
    N'@P1 varchar(255),@P2 varchar(255)',
    N'SELECT * FROM Sales.SalesOrderHeader AS h INNER JOIN Sales.SalesOrderDetail AS d ON h.SalesOrderID = d.SalesOrderID WHERE h.OrderDate BETWEEN @P1 AND @P2',
    @p5 OUTPUT,
    @p6 OUTPUT,
    @p7 OUTPUT,
    '20040101',
    '20050101'

SELECT @p1, @p2, @p5, @p6, @p7;

You notice that the plan for the SELECT query in the call to sp_cursorprepexec is using a merge join, but you want to use a hash join. The query submitted by using sp_cursorprepexec is parameterized, including both a query string and a parameter string. You can create the following plan guide to change the choice of plan by using the query and parameter strings exactly as they appear, character for character, in the call to sp_cursorprepexec.

EXEC sp_create_plan_guide
    @name = N'APICursorGuide',
    @stmt = N'SELECT * FROM Sales.SalesOrderHeader AS h
              INNER JOIN Sales.SalesOrderDetail AS d
                ON h.SalesOrderID = d.SalesOrderID
              WHERE h.OrderDate BETWEEN @P1 AND @P2',
    @type = N'SQL',
    @module_or_batch = NULL,
    @params = N'@P1 varchar(255),@P2 varchar(255)',
    @hints = N'OPTION(HASH JOIN)';

Subsequent executions of this query by the application are affected by this plan guide, and a hash join is used to process the query.

E. Create a plan guide by obtaining the XML showplan from a cached plan

The following example creates a plan guide for a simple ad hoc SQL statement. The desired query plan for this statement is provided in the plan guide by specifying the XML showplan for the query directly in the @hints parameter. The example first executes the SQL statement to generate a plan in the plan cache. For the purposes of this example, it's assumed that the generated plan is the desired plan and no further query tuning is required. The XML showplan for the query is obtained by querying the sys.dm_exec_query_stats, sys.dm_exec_sql_text, and sys.dm_exec_text_query_plan dynamic management views and is assigned to the @xml_showplan variable. The @xml_showplan variable is then passed to the sp_create_plan_guide statement in the @hints parameter. Or, you can create a plan guide from a query plan in the plan cache by using the sp_create_plan_guide_from_handle stored procedure.

USE AdventureWorks2022;
GO

SELECT City,
    StateProvinceID,
    PostalCode
FROM Person.Address
ORDER BY PostalCode DESC;
GO

DECLARE @xml_showplan NVARCHAR(MAX);

SET @xml_showplan = (
    SELECT query_plan
    FROM sys.dm_exec_query_stats AS qs
    CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS st
    CROSS APPLY sys.dm_exec_text_query_plan(qs.plan_handle, DEFAULT, DEFAULT) AS qp
    WHERE st.TEXT LIKE N'SELECT City, StateProvinceID, PostalCode FROM Person.Address ORDER BY PostalCode DESC;%'
);

EXEC sp_create_plan_guide @name = N'Guide1_from_XML_showplan',
    @stmt = N'SELECT City, StateProvinceID, PostalCode FROM Person.Address ORDER BY PostalCode DESC;',
    @type = N'SQL',
    @module_or_batch = NULL,
    @params = NULL,
    @hints = @xml_showplan;
GO

Bendrinti naudojant

sp_create_plan_guide (Transact-SQL)

Syntax

Arguments

[ @name = ] N'name'

[ @stmt = ] N'stmt'

[ @type = ] { N'OBJECT' | N'SQL' | N'TEMPLATE' }

[ @module_or_batch = ] { N' [ schema_name. ] object_name' | N'batch_text' }

[ @params = ] N'@parameter_name data_type [ ,... n ]'

[ @hints = ] { N'OPTION ( query_hint [ , ...n ] )' | N'XML_showplan' }

Remarks

Plan guide matching requirements

Plan guide effect on the plan cache

Permissions

Examples

A. Create a plan guide of type OBJECT for a query in a stored procedure

B. Create a plan guide of type SQL for a stand-alone query

C. Create a plan guide of type TEMPLATE for the parameterized form of a query

D. Create a plan guide on a query submitted by using an API cursor request

E. Create a plan guide by obtaining the XML showplan from a cached plan

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sp_create_plan_guide (Transact-SQL)

Syntax

Arguments

[ @name = ] N'name'

[ @stmt = ] N'stmt'

[ @type = ] { N'OBJECT' | N'SQL' | N'TEMPLATE' }

[ @module_or_batch = ] { N' [ schema_name. ] object_name' | N'batch_text' }

[ @params = ] N'@parameter_name data_type [ ,... n ]'

[ @hints = ] { N'OPTION ( query_hint [ , ...n ] )' | N'XML_showplan' }

Remarks

Plan guide matching requirements

Plan guide effect on the plan cache

Permissions

Examples

A. Create a plan guide of type OBJECT for a query in a stored procedure

B. Create a plan guide of type SQL for a stand-alone query

C. Create a plan guide of type TEMPLATE for the parameterized form of a query

D. Create a plan guide on a query submitted by using an API cursor request

E. Create a plan guide by obtaining the XML showplan from a cached plan

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