sys.dm_exec_query_stats (Transact-SQL)

sys.dm_exec_query_stats (Transact-S...

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SQL Server 2005

SQL Server 2008 Books Online (June 2009)

sys.dm_exec_query_stats (Transact-SQL)

Returns aggregate performance statistics for cached query plans. The view contains one row per query statement within the cached plan, and the lifetime of the rows are tied to the plan itself. When a plan is removed from the cache, the corresponding rows are eliminated from this view.

Note:
An initial query of sys.dm_exec_query_stats might produce inaccurate results if there is a workload currently executing on the server. More accurate results may be determined by rerunning the query.

Column name	Data type	Description
sql_handle	varbinary(64)	Is a token that refers to the batch or stored procedure that the query is part of. sql_handle, together with statement_start_offset and statement_end_offset, can be used to retrieve the SQL text of the query by calling the sys.dm_exec_sql_text dynamic management function.
statement_start_offset	int	Indicates, in bytes, beginning with 0, the starting position of the query that the row describes within the text of its batch or persisted object.
statement_end_offset	int	Indicates, in bytes, starting with 0, the ending position of the query that the row describes within the text of its batch or persisted object. A value of -1 indicates the end of the batch.
plan_generation_num	bigint	A sequence number that can be used to distinguish between instances of plans after a recompile.
plan_handle	varbinary(64)	A token that refers to the compiled plan that the query is part of. This value can be passed to the sys.dm_exec_query_plan dynamic management function to obtain the query plan.
creation_time	datetime	Time at which the plan was compiled.
last_execution_time	datetime	Last time at which the plan was executed.
execution_count	bigint	Number of times that the plan has been executed since it was last compiled.
total_worker_time	bigint	Total amount of CPU time, in microseconds, that was consumed by executions of this plan since it was compiled.
last_worker_time	bigint	CPU time, in microseconds, that was consumed the last time the plan was executed.
min_worker_time	bigint	Minimum CPU time, in microseconds, that this plan has ever consumed during a single execution.
max_worker_time	bigint	Maximum CPU time, in microseconds, that this plan has ever consumed during a single execution.
total_physical_reads	bigint	Total number of physical reads performed by executions of this plan since it was compiled.
last_physical_reads	bigint	Number of physical reads performed the last time the plan was executed.
min_physical_reads	bigint	Minimum number of physical reads that this plan has ever performed during a single execution.
max_physical_reads	bigint	Maximum number of physical reads that this plan has ever performed during a single execution.
total_logical_writes	bigint	Total number of logical writes performed by executions of this plan since it was compiled.
last_logical_writes	bigint	Number of logical writes performed the last time the plan was executed.
min_logical_writes	bigint	Minimum number of logical writes that this plan has ever performed during a single execution.
max_logical_writes	bigint	Maximum number of logical writes that this plan has ever performed during a single execution.
total_logical_reads	bigint	Total number of logical reads performed by executions of this plan since it was compiled.
last_logical_reads	bigint	Number of logical reads performed the last time the plan was executed.
min_logical_reads	bigint	Minimum number of logical reads that this plan has ever performed during a single execution.
max_logical_reads	bigint	Maximum number of logical reads that this plan has ever performed during a single execution.
total_clr_time	bigint	Time, in microseconds, consumed inside Microsoft .NET Framework common language runtime (CLR) objects by executions of this plan since it was compiled. The CLR objects can be stored procedures, functions, triggers, types, and aggregates.
last_clr_time	bigint	Time consumed by execution inside .NET Framework CLR objects during the last execution of this plan. The CLR objects can be stored procedures, functions, triggers, types, and aggregates.
min_clr_time	bigint	Minimum time, in microseconds, that this plan has ever consumed inside .NET Framework CLR objects during a single execution. The CLR objects can be stored procedures, functions, triggers, types, and aggregates.
max_clr_time	bigint	Maximum time, in microseconds, that this plan has ever consumed inside the .NET Framework CLR during a single execution. The CLR objects can be stored procedures, functions, triggers, types, and aggregates.
total_elapsed_time	bigint	Total elapsed time, in microseconds, for completed executions of this plan.
last_elapsed_time	bigint	Elapsed time, in microseconds, for the most recently completed execution of this plan.
min_elapsed_time	bigint	Minimum elapsed time, in microseconds, for any completed execution of this plan.
max_elapsed_time	bigint	Maximum elapsed time, in microseconds, for any completed execution of this plan.
query_hash	Binary(8)	Binary hash value calculated on the query and used to identify queries with similar logic. You can use the query hash to determine the aggregate resource usage for queries that differ only by literal values. For more information, see Finding and Tuning Similar Queries by Using Query and Query Plan Hashes.
query_plan_hash	binary(8)	Binary hash value calculated on the query execution plan and used to identify similar query execution plans. You can use query plan hash to find the cumulative cost of queries with similar execution plans. For more information, see Finding and Tuning Similar Queries by Using Query and Query Plan Hashes.

Permissions

Requires VIEW SERVER STATE permission on server.

Remarks

Statistics in the view are updated when a query is completed.

Examples

A. Finding the TOP N queries

The following example returns information about the top five queries ranked by average CPU time. This example aggregates the queries according to their query hash so that logically equivalent queries are grouped by their cumulative resource consumption.

USE AdventureWorks;
GO
SELECT TOP 5 query_stats.query_hash AS "Query Hash", 
    SUM(query_stats.total_worker_time) / SUM(query_stats.execution_count) AS "Avg CPU Time",
    MIN(query_stats.statement_text) AS "Statement Text"
FROM 
    (SELECT QS.*, 
    SUBSTRING(ST.text, (QS.statement_start_offset/2) + 1,
    ((CASE statement_end_offset 
        WHEN -1 THEN DATALENGTH(st.text)
        ELSE QS.statement_end_offset END 
            - QS.statement_start_offset)/2) + 1) AS statement_text
     FROM sys.dm_exec_query_stats AS QS
     CROSS APPLY sys.dm_exec_sql_text(QS.sql_handle) as ST) as query_stats
GROUP BY query_stats.query_hash
ORDER BY 2 DESC;
GO

Reference

Dynamic Management Views and Functions (Transact-SQL)
Execution Related Dynamic Management Views and Functions (Transact-SQL)
sys.dm_exec_sql_text (Transact-SQL)
sys.dm_exec_query_plan (Transact-SQL)

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