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sys.dm_exec_query_profiles (Transact-SQL)

  • Artikkeli

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

Monitors real time query progress while the query is in execution. For example, use this DMV to determine which part of the query is running slow. Join this DMV with other system DMVs using the columns identified in the description field. Or, join this DMV with other performance counters (such as Performance Monitor, xperf) by using the timestamp columns.

Table Returned

The counters returned are per operator per thread. The results are dynamic and do not match the results of existing options such as SET STATISTICS XML ON which only create output when the query is finished.

Column name Data type Description
session_id smallint Identifies the session in which this query runs. References dm_exec_sessions.session_id.
request_id int Identifies the target request. References dm_exec_sessions.request_id.
sql_handle varbinary(64) Is a token that uniquely identifies the batch or stored procedure that the query is part of. References dm_exec_query_stats.sql_handle.
plan_handle varbinary(64) Is a token that uniquely identifies a query execution plan for a batch that has executed and its plan resides in the plan cache, or is currently executing. References dm_exec_query_stats.plan_handle.
physical_operator_name nvarchar(256) Physical operator name.
node_id int Identifies an operator node in the query tree.
thread_id int Distinguishes the threads (for a parallel query) belonging to the same query operator node.
task_address varbinary(8) Identifies the SQLOS task that this thread is using. References dm_os_tasks.task_address.
row_count bigint Number of rows returned by the operator so far.
rewind_count bigint Number of rewinds so far.
rebind_count bigint Number of rebinds so far.
end_of_scan_count bigint Number of end of scans so far.
estimate_row_count bigint Estimated number of rows. It can be useful to compare to estimated_row_count to the actual row_count.
first_active_time bigint The time, in milliseconds, when the operator was first called.
last_active_time bigint The time, in milliseconds, when the operator was last called.
open_time bigint Timestamp when open (in milliseconds).
first_row_time bigint Timestamp when first row was opened (in milliseconds).
last_row_time bigint Timestamp when last row was opened(in milliseconds).
close_time bigint Timestamp when close (in milliseconds).
elapsed_time_ms bigint Total elapsed time (in milliseconds) used by the target node's operations so far.
cpu_time_ms bigint Total CPU time (in milliseconds) use by target node's operations so far.
database_id smallint ID of the database that contains the object on which the reads and writes are being performed.
object_id int The identifier for the object on which the reads and writes are being performed. References sys.objects.object_id.
index_id int The index (if any) the rowset is opened against.
scan_count bigint Number of table/index scans so far.
logical_read_count bigint Number of logical reads so far.
physical_read_count bigint Number of physical reads so far.
read_ahead_count bigint Number of read-aheads so far.
write_page_count bigint Number of page-writes so far due to spilling.
lob_logical_read_count bigint Number of LOB logical reads so far.
lob_physical_read_count bigint Number of LOB physical reads so far.
lob_read_ahead_count bigint Number of LOB read-aheads so far.
segment_read_count int Number of segment read-aheads so far.
segment_skip_count int Number of segments skipped so far.
actual_read_row_count bigint Number of rows read by an operator before the residual predicate was applied.
estimated_read_row_count bigint Applies to: Beginning with SQL Server 2016 (13.x) SP1.
Number of rows estimated to be read by an operator before the residual predicate was applied.

General Remarks

If the query plan node does not have any I/O, all the I/O-related counters are set to NULL.

The I/O-related counters reported by this DMV are more granular than the ones reported by SET STATISTICS IO in the following two ways:

  • SET STATISTICS IO groups the counters for all I/O to a given table together. With this DMV you will get separate counters for every node in the query plan that performs I/O to the table.

  • If there is a parallel scan, this DMV reports counters for each of the parallel threads working on the scan.

Starting with SQL Server 2016 (13.x) SP1, the standard query execution statistics profiling infrastructure exists side-by-side with a lightweight query execution statistics profiling infrastructure. SET STATISTICS XML ON and SET STATISTICS PROFILE ON always use the standard query execution statistics profiling infrastructure. For sys.dm_exec_query_profiles to be populated, one of the query profiling infrastructures must be enabled. For more information, see Query Profiling Infrastructure.

Note

The query under investigation has to start after the query profiling infrastructure has been enabled, enabling it after the query started will not produce results in sys.dm_exec_query_profiles. For more information on how to enable the query profiling infrastructures, see Query Profiling Infrastructure.

Permissions

  • On SQL Server and Azure SQL Managed Instance, requires VIEW DATABASE STATE permission and membership of the db_owner database role.
  • On Azure SQL Database Premium Tiers, requires the VIEW DATABASE STATE permission in the database.
  • On Azure SQL Database Basic, S0, and S1 service objectives, and for databases in elastic pools, the server admin account or the Microsoft Entra admin account is required. On all other SQL Database service objectives, the VIEW DATABASE STATE permission is required in the database.

Permissions for SQL Server 2022 and later

Requires VIEW DATABASE PERFORMANCE STATE permission on the database.

Examples

Step 1: Login to a session in which you plan to run the query you will analyze with sys.dm_exec_query_profiles. To configure the query for profiling use SET STATISTICS PROFILE ON. Run your query in this same session.

--Configure query for profiling with sys.dm_exec_query_profiles  
SET STATISTICS PROFILE ON;  
GO  

--Or enable query profiling globally under SQL Server 2016 SP1 or above (not needed in SQL Server 2019)  
DBCC TRACEON (7412, -1);  
GO 
  
--Next, run your query in this session, or in any other session if query profiling has been enabled globally

Step 2: Login to a second session that is different from the session in which your query is running.

The following statement summarizes the progress made by the query currently running in session 54. To do this, it calculates the total number of output rows from all threads for each node, and compares it to the estimated number of output rows for that node.

--Run this in a different session than the session in which your query is running. 
--Note that you may need to change session id 54 below with the session id you want to monitor.
SELECT node_id,physical_operator_name, SUM(row_count) row_count, 
  SUM(estimate_row_count) AS estimate_row_count, 
  CAST(SUM(row_count)*100 AS float)/SUM(estimate_row_count)  
FROM sys.dm_exec_query_profiles   
WHERE session_id=54
GROUP BY node_id,physical_operator_name  
ORDER BY node_id;

See Also

Dynamic Management Views and Functions (Transact-SQL)
Execution Related Dynamic Management Views and Functions (Transact-SQL)