SQL Server通过动态视图里查找阻塞的会话
对于阻塞我们可以通过动态视图dm_exec_requests、dm_tran_locks等关联通过构建递归式树形结构来查找出阻塞超过30秒的会话。
WITH Blocked_Sessions AS ( -- 找到所有阻塞的会话 SELECT sys.dm_exec_requests.blocking_session_id AS lead_session_id, sys.dm_exec_requests.blocking_session_id AS blocking_session_id , 0 Cnt FROM sys.dm_exec_requests WHERE blocking_session_id <> 0 AND blocking_session_id NOT IN (SELECT session_id FROM sys.dm_exec_requests WHERE sys.dm_exec_requests.blocking_session_id <> 0) UNION ALL -- 遍历所有的会话(构建树型关系) SELECT Blocked_Sessions.lead_session_id, sys.dm_exec_requests.session_id, 1 Cnt FROM sys.dm_exec_requests JOIN Blocked_Sessions ON Blocked_Sessions.blocking_session_id = sys.dm_exec_requests.blocking_session_id ), Blocked AS ( SELECT lead_session_id, SUM(Cnt) AS sessions_blocked FROM Blocked_Sessions GROUP BY lead_session_id) SELECT Blocked.*, DATEDIFF(s, Sess.last_request_start_time, getdate()) seconds_blocking, ISNULL(Req.status,'sleeping') [status], SqlText.text [sql_text], STUFF((SELECT DISTINCT ISNULL(', ' + db.name,'') FROM sys.databases db JOIN sys.dm_tran_locks lcks ON db.database_id = lcks.resource_database_id WHERE lcks.request_session_id = Sess.session_id ORDER BY ISNULL(', ' + db.name,'') FOR XML PATH(''),TYPE).value('.','VARCHAR(MAX)') ,1,2,'') AS database_list , Conn.client_net_address, Sess.login_name FROM sys.dm_exec_connections Conn LEFT OUTER JOIN sys.dm_exec_sessions Sess ON Conn.session_id = Sess.session_id JOIN Blocked ON Blocked.lead_session_id = Sess.session_id CROSS APPLY sys.dm_exec_sql_text(Conn.most_recent_sql_handle) SqlText LEFT JOIN sys.dm_exec_requests Req ON Req.session_id = Sess.session_id WHERE Blocked.sessions_blocked >= 1 -- 过滤阻塞超过30秒的记录 AND DATEDIFF(s, Sess.last_request_start_time, getdate()) > 30;