sp_who2 is a well known utility that shows what spids are currently executing. However the information it shows is relatively limited. For example, it only shows the type of command executing as SELECT, DELETE etc, with no reference to the actual underlying SQL executing.
Knowing what SQL is executing can be vital in debugging why a query is taking a long time, or determining if it is being blocked. It can also be useful in showing the progress of a stored procedure i.e. what statement within the stored procedure is currently executing.
The utility makes use of Dynamic Management Views (DMVs)
The Dynamic Management View (DMV) sys.db_exec_requests shows which requests are currently executing, the information shown includes the handle to the whole SQL text of the batch or stored procedure (sql_handle), together with offsets relating to the section of SQL within the batch that is currently executing (statement_start_offset and statement_end_offset).
To determine the current section of SQL currently executing, we need to call the Dynamic Management Function (DMF) sys.dm_exec_sql_text, passing in the handle of the SQL batch that is currently executing, and then apply the relevant offsets.
We can get more information about the query by combining the sys.db_exec_requests DMV with the sys.processes system view (joined on spid/session_id). This information includes who is executing the query, the machine they are running from, and the name of the database.
The utility selects relevant fields from the sys.db_exec_requests and sys.sysprocesses views. The selected fields are described here.
|Column name||Data type||Description|
|spid||smallint||SQL Server process ID.|
|ecid||smallint||Execution context ID used to uniquely identify the subthreads operating on behalf of a single process.|
|dbid||smallint||ID of the database currently being used by the process.|
|nt_username||nchar(128)||Windows user name for the process, if using Windows Authentication, or a trusted connection.|
|status||nchar(30)||Process ID status. For example, running and sleeping.|
|wait_type||bigint||Current wait time in milliseconds.|
|Individual Query||varchar||SQL Statement currently running.|
|Parent Query||varchar||Routine that contains the Individual Query.|
|program_name||nchar(128)||Name of the application program.|
|Hostname||nchar(128)||Name of the workstation.|
|nt_domain||nchar(128)||Microsoft Windows domain for the client, if using Windows Authentication, or a trusted connection.|
|Start_time||datetime||Time when the request is scheduled to run.|
CREATE PROC [dbo].[dba_WhatSQLIsExecuting]
Purpose: Shows what individual SQL statements are currently executing.
1. exec YourServerName.master.dbo.dba_WhatSQLIsExecuting
— Do not lock anything, and do not get held up by any locks.
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
— What SQL Statements Are Currently Running?
SELECT [Spid] = session_Id
, [Database] = DB_NAME(sp.dbid)
, [User] = nt_username
, [Status] = er.status
, [Wait] = wait_type
, [Individual Query] = SUBSTRING (qt.text,
(CASE WHEN er.statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2
ELSE er.statement_end_offset END –
,[Parent Query] = qt.text
, Program = program_name
FROM sys.dm_exec_requests er
INNER JOIN sys.sysprocesses sp ON er.session_id = sp.spid
CROSS APPLY sys.dm_exec_sql_text(er.sql_handle)as qt
WHERE session_Id > 50 — Ignore system spids.
AND session_Id NOT IN (@@SPID) — Ignore this current statement.
ORDER BY 1, 2
This utility allows you to observe the progress of a stored procedure or SQL batch, additionally it can be used to identify the cause of a long running query or blocking query.
Since the utility uses existing data held in DMVs it is relatively non-intrusive and should have little affect on performance.
If the identified queries are long running or causing blocking, it might be worthwhile running them inside the Database Tuning Advisor (DTA), this might identify the cause of the slow running (e.g. a missing index).
For more information visit : http://www.sqlservercentral.com/articles/DMV/64425/