初涉SQL Server性能问题（3/4）：列出阻塞的会话

在 初涉SQL Server性能问题（2/4）里，我们讨论了列出等待资源或正运行的会话脚本。这篇文章我们会看看如何列出包含具体信息的话阻塞会话清单。

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

这个脚本会列出被阻塞和正阻塞的语句信息，帮助我们进行问题分析。下面的脚本会帮助我们列出已经打开事务但未活动的会话，即打开事务，但上30秒内都没执行任何语句的会话。

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

参考文章：

http://www.sqlservercentral.com/blogs/practicalsqldba/2012/09/24/sql-server-part-3-approaching-database-server-performance-issue-/