Sunday, 25 June 2017

Getting the full name of SQL Jobs including the steps in execution

While monitoring a database server, we may need to know some details about the sessions, connections and requests that migh be causing performance or blocking issues so that we can take actions to fix them. In doing so, one very important piece of information is the program name that is connected to the database engine. Broadly, it is posible to see the program name in detail by using system stored procedures or DMVs such as 'sp_who2' and 'sys.dm_exec_sessions'. Nevertheless, not every name of the programs may be easy to interpret, especially when it comes to SQL Jobs. For instance, if you detected that a SQL Job is the root of the problem and then needed to know which SQL Job it is, the column program_name of 'sp_who2' or 'sys.dm_exec_sessions' woud only give us the SQL Job ID based on the following format:

SQLAgent - TSQL JobStep (Job 0x2613DA812CD2D248A9BA377DE6DEF355 : Step 1)

Obviously, we cannot do much with that info because there is no SQL Job name, and even worse, no SQL Job step name. However,  we can figure out the name of the SQL Job in msdb.dbo.sysjobs by using the ID.

SELECT * FROM msdb.dbo.sysjobs WHERE job_id=0x2613DA812CD2D248A9BA377DE6DEF355

Despite the fact that it may be relativily easy to get the name of the SQL Job, it is not enough because it is of paramount importance to know the name of the step in execution, and keep in mind that doing this manually this every time when needed is going to be an uphill battle as it is arduous and not optimal, especially if there are many SQL Jobs running and causing struggles. Thinking of this situation, I created a script to automate the task of figuring out details related to SQL Jobs such as the name and also the step name that is running. To be more precise, this logic is inside a function called "ufn_GetJobStepNameDesc" that takes the value of the "program_name" column and returns the name of the SQL Job and the step in execution. Let's take a look at the following code whereby we also filter out the sessions used by SQL Jobs.

SELECT session_id, login_time, login_name, [status], writes,
       logical_reads, [language], DB_NAME(database_id) DatabaseName,
          dbo.ufn_GetJobStepNameDesc([program_name]) AS SQLJobDescription
FROM sys.dm_exec_sessions where [program_name] like 'SQLAgent - TSQL%'
As you can see, I have highlighted the use of the function, and also added other important columns to look at as part of monitoring. So, using dbo.ufn_GetJobStepNameDesc([program_name]) the final outcome would be like this: SQLAgent - TSQL JobStep "<Name of the job step>" (Job: <Job name>).  For instance: SQLAgent - TSQL JobStep "Updating_Accounts" (Job: SAP_Financial_Process)
Here I share with you my script so that you can check it thoroughly and then make the most out if it.
USE [master]
GO
CREATE FUNCTION  [dbo].[ufn_GetJobStepNameDesc] (@step_name_desc VARCHAR(MAX))
RETURNS VARCHAR(max)
AS
BEGIN
       DECLARE @full_step_name_desc VARCHAR(MAX)
       DECLARE @jobstep_id_start INT
       DECLARE @jobstep_id_len INT
       DECLARE @jobstep_id INT
       SELECT @jobstep_id_start=CHARINDEX(': Step', @step_name_desc)+7, @jobstep_id_len=CHARINDEX(')', @step_name_desc)-@jobstep_id_start
       set @jobstep_id= CAST(SUBSTRING(@step_name_desc, @jobstep_id_start,@jobstep_id_len) AS INT)

       DECLARE @job_id_start INT
       DECLARE @job_id_len INT
       DECLARE @hexa_job_id VARBINARY(MAX)
       SELECT @job_id_start=CHARINDEX('(Job 0', @step_name_desc)+5,  @job_id_len=CHARINDEX(':', @step_name_desc)-@job_id_start
       SET @hexa_job_id=CONVERT( VARBINARY, RTRIM(LTRIM(SUBSTRING(@step_name_desc, @job_id_start,@job_id_len))),1)
      
       SELECT @full_step_name_desc='SQLAgent - TSQL JobStep "' + step_name+'" (Job: ' + j.[name] +')'
       FROM msdb.dbo.sysjobsteps js
            INNER JOIN msdb.dbo.sysjobs j ON j.job_id=js.job_id
       WHERE step_id=@jobstep_id and j.job_id=CAST(@hexa_job_id  AS UNIQUEIDENTIFIER)
       RETURN ( @full_step_name_desc)
END
That is all for now, I hope you find this post helpful. Let me know any remarks you may have. Stay tuned.

Monday, 19 June 2017

Error: could not obtain information about Windows NT group/user

Without any doubt, at times there is a need to use extended stored procedures in SQL Server, for instance, the following error may be raised while using 'xp_logininfo' to get information about domain account 'MyDomainMyAccount' (the account you are logged within SQL Server). The error may also appear when a SQL job, whose owner is a windows account, tries to authenticate against the Active Directory(AD) and this validation fails because of internal security reasons between SQL Server and the AD.

Error: 15404, State: 19. Could not obtain information about Windows NT group/user ‘MyDomainMyAccount’, error code 0x5.

In order to solve this error your Network Administrator has to enable ‘Allowed to authenticate’ security setting on the domain controllers computer object for the account 'MyDomainMyAccount' in the domain 'MyDomain' by following these steps:
  1. logon to the Domain Controller of domain 'MyDomain'
  2. open Active Directory Users and Computers (dsa.msc)
  3. enable the ‘Advanced Features’ under the menu ‘View’
  4. navigate to the domain controllers computer object and open the property window
  5. click on the security tab
  6. add the SQL Service account 'MyDomainMyAccount' and enable the setting ‘Allowed to authenticate’
  7. click OK to close the window
  8. repeat steps 4-7 on each Domain Controller computer object
Having done that, 'xp_logininfo' will run successfully bringing the information from the Active Directory. That is all for now, let me know any remarks you may have. Thanks for reading. Stay tuned.

Friday, 2 June 2017

sys.dm_exec_requests: total_elapsed_time column might return inconsistent data

Developing useful scripts for administration purposes, I have found a bug with respect to data recollected by 'sys.dm_exec_requests' dynamic management view on SQL Server 2008 R2 SP2 while I was analysing the total elapsed time for a particular SQL query. Let me expand on what I am saying. I did detect an error in the 17th second of the execution with 'session_id' equal to 63 (see it in the picture). Following the sequence of each result in the execution of queries, I need to draw your attention to the second query and its second column where the total elapsed time according to 'sys.dm_exec_requests' should be 17 and not 938 seconds since the previous one was 16. Now, checking the value of the third column (calculated by subtracting the 'start_time' value from GETDATE function), you will verify that this time is accurate whereas the second one is false. The value for the second and third columns should be the same but they are different.



To sum up, for this particular and real case, the column 'total_elapsed_time' returns inconsistent information about elapsed execution time of a process when it exceeds 16 seconds. Despite of the fact that I have not seen the same issue in other versions like SQL Server 2012/2014/2016/2017, it is better not to trust in DMVs so much. Therefore, I suggest working with caution. That is all for now, let me know any remark you may have. Stay tuned.

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