Updated sys.dm_os_waiting_tasks script to add query DOP

Edit 10/30/19: the latest version of this script, with additions and adapted for newer versions is here.

A question came up in class today about easily seeing the degree of parallelism for parallel query plans, so I’ve updated my waiting tasks script to pull in the dop field from sys.dm_exec_query_memory_grants. I’ve also added in a URL field that points into the new waits library, and shortened some of the column names.

Here it is for your use.

Enjoy!

(Note that ‘text’ on one line does not have delimiters because that messes up the code formatting plugin):

/*============================================================================
  File:     WaitingTasks.sql

  Summary:  Snapshot of waiting tasks

  SQL Server Versions: 2005 onwards
------------------------------------------------------------------------------
  Written by Paul S. Randal, SQLskills.com

  (c) 2016, SQLskills.com. All rights reserved.

  For more scripts and sample code, check out 
    http://www.SQLskills.com

  You may alter this code for your own *non-commercial* purposes. You may
  republish altered code as long as you include this copyright and give due
  credit, but you must obtain prior permission before blogging this code.
  
  THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF 
  ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
  TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
  PARTICULAR PURPOSE.
============================================================================*/
SELECT
    [owt].[session_id] AS [SPID],
    [owt].[exec_context_id] AS [Thread],
    [ot].[scheduler_id] AS [Scheduler],
    [owt].[wait_duration_ms] AS [wait_ms],
    [owt].[wait_type],
    [owt].[blocking_session_id] AS [Blocking SPID],
    [owt].[resource_description],
    CASE [owt].[wait_type]
        WHEN N'CXPACKET' THEN
            RIGHT ([owt].[resource_description],
                CHARINDEX (N'=', REVERSE ([owt].[resource_description])) - 1)
        ELSE NULL
    END AS [Node ID],
    [eqmg].[dop] AS [DOP],
    [er].[database_id] AS [DBID],
    CAST ('https://www.sqlskills.com/help/waits/' + [owt].[wait_type] as XML) AS [Help/Info URL],
    [eqp].[query_plan],
    [est].text
FROM sys.dm_os_waiting_tasks [owt]
INNER JOIN sys.dm_os_tasks [ot] ON
    [owt].[waiting_task_address] = [ot].[task_address]
INNER JOIN sys.dm_exec_sessions [es] ON
    [owt].[session_id] = [es].[session_id]
INNER JOIN sys.dm_exec_requests [er] ON
    [es].[session_id] = [er].[session_id]
FULL JOIN sys.dm_exec_query_memory_grants [eqmg] ON
    [owt].[session_id] = [eqmg].[session_id]
OUTER APPLY sys.dm_exec_sql_text ([er].[sql_handle]) [est]
OUTER APPLY sys.dm_exec_query_plan ([er].[plan_handle]) [eqp]
WHERE
    [es].[is_user_process] = 1
ORDER BY
    [owt].[session_id],
    [owt].[exec_context_id];
GO

9 thoughts on “Updated sys.dm_os_waiting_tasks script to add query DOP

  1. Thanks Paul.

    Also, now you have your awesome wait type library you could consider adding an extra line into the script

    Cast (‘https://www.sqlskills.com/help/’ + [owt].[wait_type] as XML) as URL

    This provides a direct hyper link to your new resource

  2. Thank you Paul.

    In 1 earlier article you mentioned Dop is calculated/used per operator. If my query has 2 operators in query plan, 1 using 4 threads and other 6 threads. What will be final DOP in DMV. Will it be 6 or 4 or 6+4=10?

    Thank you always

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