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sys.dm_exec_plan_attributes

Updated: 12 December 2006

Returns one row per plan attribute for the plan specified by the plan handle. You can use this table-valued function to get details about a particular plan, such as the cache key values or the number of current simultaneous executions of the plan.

ms189472.note(en-US,SQL.90).gifNote:
Some of the information returned through this function maps to the sys.syscacheobjects backward compatibility view.


sys.dm_exec_plan_attributes (plan_handle)
plan_handle

Uniquely identifies a query plan for a batch that has executed and whose plan resides in the plan cache. plan_handle is varbinary(64). The plan handle can be obtained from the sys.dm_exec_cached_plans dynamic management view.

Column name Data type Description

attribute

varchar(128)

Name of the attribute associated with this plan. One of the following:

set_options int Indicates the option values that the plan was compiled with.
objectid int One of the main keys used for looking up an object in the cache. This is the object ID stored in sys.objects for database objects (procedures, views, triggers, and so on). For plans of type "Adhoc" or "Prepared", it is an internal hash of the batch text.
dbid int Is the ID of the database where the entity for which we have the plan resides. For ad hoc or prepared plans, it is the database ID from which the batch is executed.
dbid_execute int For system objects stored in the Resource database, the database ID from which the cached plan is executed. For all other cases it is 0.
user_id int ID of the schema that contains the object. A value of -2 indicates that the batch submitted does not depend on implicit name resolution and can be shared among different users. This is the preferred method.
language_id smallint ID of the language of the connection that created the cache object. For more information, see sys.syslanguages (Transact-SQL).
date_format smallint Date format of the connection that created the cache object. For more information, see SET DATEFORMAT (Transact-SQL).
date_first tinyint Date first value. For more information, see SET DATEFIRST (Transact-SQL).
status int Internal status bits that are part of the cache lookup key.
required_cursor_options int Cursor options specified by the user such as the cursor type.
acceptable_cursor_options int Cursor options that SQL Server may implicitly convert to in order to support the execution of the statement. For example, the user may specify a dynamic cursor, but the query optimizer is permitted to convert this cursor type to a static cursor. For more information, see Using Implicit Cursor Conversions.
inuse_exec_context int Number of currently executing batches that are using the query plan. For more information about execution context and query plans, see Execution Plan Caching and Reuse.
free_exec_context int Number of cached execution contexts for the query plan that are not being currently used.
hits_exec_context int Number of times the execution context was obtained from the plan cache and reused, saving the overhead of recompiling the SQL statement. The value is an aggregate for all batch executions so far.
misses_exec_context int Number of times that an execution context could not be found in the plan cache, resulting in the creation of a new execution context for the batch execution.
removed_exec_context int Number of execution contexts that have been removed because of memory pressure on the cached plan.
inuse_cursors int Number of currently executing batches containing one or more cursors that are using the cached plan.
free_cursors int Number of idle or free cursors for the cached plan.
hits_cursors int Number of times that an inactive cursor was obtained from the cached plan and reused. The value is an aggregate for all batch executions so far.
misses_cursors int Number of times that an inactive cursor could not be found in the cache.
removed_cursors int Number of cursors that have been removed because of memory pressure on the cached plan.
sql_handle varbinary(64) The SQL handle for the batch.
Attribute Data type Description

value

sql_variant

Value of the attribute that is associated with this plan.

is_cache_key

bit

Indicates whether the attribute is used as part of the cache lookup key for the plan.

Set Options

Copies of the same compiled plan might differ only by the value in the set_options column. This indicates that different connections are using different sets of SET options for the same query. Using different sets of options is usually undesirable because it can cause extra compilations, less plan reuse, and plan cache inflation because of multiple copies of plans in the cache. For more information, see Query Tuning Recommendations.

Evaluating Set Options

To translate the value returned in set_options to the options with which the plan was compiled, subtract the values from the set_options value, starting with the largest possible value, until you reach 0. Each value you subtract corresponds to an option that was used in the query plan. For example, if the value in set_options is 251, the options the plan was compiled with are ANSI_NULL_DFLT_ON (128), QUOTED_IDENTIFIER (64), ANSI_NULLS(32), ANSI_WARNINGS (16), CONCAT_NULL_YIELDS_NULL (8), Parallel Plan(2) and ANSI_PADDING (1).

Option Value

ANSI_PADDING

1

Parallel Plan

2

FORCEPLAN

4

CONCAT_NULL_YIELDS_NULL

8

ANSI_WARNINGS

16

ANSI_NULLS

32

QUOTED_IDENTIFIER

64

ANSI_NULL_DFLT_ON

128

ANSI_NULL_DFLT_OFF

256

NoBrowseTable

Indicates that the plan does not use a work table to implement a FOR BROWSE operation.

512

TriggerOneRow

Indicates that the plan contains single row optimization for AFTER and INSTEAD OF triggers. That is, if only one row is affected in the inserted or deleted tables, this option is set. Applies to Transact-SQL triggers and CLR triggers that perform in-process data access.

1024

ResyncQuery

Indicates that the query was submitted by internal system stored procedures.

2048

ARITH_ABORT

4096

NUMERIC_ROUNDABORT

8192

DATEFIRST

16384

DATEFORMAT

32768

LanguageID

65536

UPON

Indicates that the database option PARAMETERIZATION was set to FORCED when the plan was compiled.

131072

Cursors

Inactive cursors are cached in a compiled plan so that the memory used to store the cursor can be reused by concurrent users of cursors. For example, suppose that a batch declares and uses a cursor without deallocating it. If there are two users executing the same batch, there will be two active cursors. Once the cursors are deallocated (potentially in different batches), the memory used to store the cursor is cached and not released. This list of inactive cursors is kept in the compiled plan. The next time a user executes the batch, the cached cursor memory will be reused and initialized appropriately as an active cursor.

Evaluating Cursor Options

To translate the value returned in required_cursor_options and acceptable_cursor_options to the options with which the plan was compiled, subtract the values from the column value, starting with the largest possible value, until you reach 0. Each value you subtract corresponds to a cursor option that was used in the query plan.

Option Value

None

0

INSENSITIVE

1

SCROLL

2

READ ONLY

4

FOR UPDATE

8

LOCAL

16

GLOBAL

32

FORWARD_ONLY

64

KEYSET

128

DYNAMIC

256

SCROLL_LOCKS

512

OPTIMISTIC

1024

STATIC

2048

FAST_FORWARD

4096

IN PLACE

8192

FOR select_statement

16384

Requires VIEW SERVER STATE permission on the server.

A. Returning the attributes for a specific plan

The following example returns all plan attributes for a specified plan. The sys.dm_exec_cached_plans dynamic management view is queried first to obtain the plan handle for the specified plan. In the second query, replace <plan_handle> with a plan handle value from the first query.

SELECT plan_handle, refcounts, usecounts, size_in_bytes, cacheobjtype, objtype 
FROM sys.dm_exec_cached_plans;
GO
SELECT attribute, value, is_cache_key
FROM sys.dm_exec_plan_attributes(<plan_handle>);
GO

B. Returning the SET options for compiled plans and the SQL handle for cached plans

The following example returns a value representing the options that each plan was compiled with. In addition, the SQL text and SQL handle are returned.

SELECT plan_handle, pvt.set_options, pvt.sql_handle, text
FROM (
    SELECT plan_handle, epa.attribute, epa.value, st.text 
    FROM sys.dm_exec_cached_plans 
        OUTER APPLY sys.dm_exec_plan_attributes(plan_handle) AS epa
        CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS st
    WHERE cacheobjtype = 'Compiled Plan') AS ecpa 
PIVOT (MAX(ecpa.value) FOR ecpa.attribute IN ("set_options", "sql_handle")) AS pvt;
GO

Release History

12 December 2006

New content:
  • Listed the attributes returned in the Attribute column.
  • Added the Remarks and Examples sections.
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