SQL Server: Part 3 : Approaching Database Server Performance Issue

In the last post, we have discussed the script to list the sessions which are waiting for resource or currently running. In this post let us see how to list the blocking sessions with required information.  

******************************************************************************************/
CREATE FUNCTION [dbo].dba_GetStatementForSpid
(  
   @spid SMALLINT  
)  
RETURNS NVARCHAR(4000)  
BEGIN  
   DECLARE @SqlHandle BINARY(20)  
   DECLARE @SqlText NVARCHAR(4000)  
   SELECT @SqlHandle = sql_handle   
      FROM sys.sysprocesses WITH (nolock) WHERE   spid = @spid  
   SELECT @SqlText = [text] FROM   
      sys.dm_exec_sql_text(@SqlHandle)  
   RETURN @SqlText  
END  
GO

/*****************************************************************************************
STEP 4: List the current blocking session information
****************************************************************************************/

SELECT
es.session_id,
es.HOST_NAME,
DB_NAME(database_id) AS DatabaseName, 
CASE WHEN es.program_name LIKE '%SQLAgent - TSQL JobStep%' THEN (SELECT 'SQL AGENT JOB: '+name FROM msdb..sysjobs WHERE job_id=MASTER.DBO.ConvertStringToBinary (LTRIM(RTRIM((SUBSTRING(es.program_name,CHARINDEX('(job',es.program_name,0)+4,35)))))) 
ELSE es.program_name END  AS program_name ,
es.login_name ,
bes.session_id AS Blocking_session_id,
MASTER.DBO.dba_GetStatementForSpid(es.session_id) AS [Statement],
bes.HOST_NAME AS Blocking_hostname,
CASE WHEN Bes.program_name LIKE '%SQLAgent - TSQL JobStep%' THEN
(SELECT 'SQL AGENT JOB: '+name FROM msdb..sysjobs WHERE job_id=
MASTER.DBO.ConvertStringToBinary 
(LTRIM(RTRIM((SUBSTRING(Bes.program_name,CHARINDEX('(job',es.program_name,0)+4,35))))))
ELSE Bes.program_name END  AS Blocking_program_name,
bes.login_name AS Blocking_login_name,
  MASTER.DBO.dba_GetStatementForSpid(bes.session_id ) AS [Blocking Statement]
FROM sys.dm_exec_requests S 
INNER JOIN sys.dm_exec_sessions  es ON es.session_id=s.session_id
INNER JOIN sys.dm_exec_sessions  bes ON bes.session_id=s.blocking_session_id



This script will list the blocked and blocking statement information and will be helpful to troubleshoot. Below script will help us to identify the sessions which have an open transaction but not active . That is, a sessions with an open transaction but not running any statement in the last 30 seconds.

/*****************************************************************************************

STEP 4: List the Open session with transaction which is not active
****************************************************************************************/
SELECT es.session_id, 
es.login_name, 
es.HOST_NAME, 
DB_NAME(SP.dbid) AS DatabaseName,
sp.lastwaittype,
est.TEXT,cn.last_read, 
cn.last_write,
CASE WHEN es.program_name LIKE '%SQLAgent - TSQL JobStep%' THEN(SELECT 'SQL AGENT JOB: '+name FROM msdb..sysjobs WHERE job_id=MASTER.DBO.ConvertStringToBinary (LTRIM(RTRIM((SUBSTRING(es.program_name,CHARINDEX('(job',es.program_name,0)+4,35)))))
)ELSE es.program_name END  AS program_name 
FROM sys.dm_exec_sessions es
INNER JOIN sys.dm_tran_session_transactions st ON es.session_id = st.session_id                INNER JOIN sys.dm_exec_connections cn ON es.session_id = cn.session_id 
INNER JOIN sys.sysprocesses SP ON SP.spid=es.session_id                 
LEFT OUTER JOIN sys.dm_exec_requests er  ON st.session_id = er.session_id   
AND er.session_id IS NULL             
CROSS APPLY sys.dm_exec_sql_text(cn.most_recent_sql_handle) est                
WHERE (DATEDIFF(SS,cn.last_read,GETDATE())+DATEDIFF(SS,cn.last_write,GETDATE()))>30
AND lastwaittype NOT IN ('BROKER_RECEIVE_WAITFOR' ,'WAITFOR')                                  GO


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