SQL Server超时诊断

连接超时

对于连接超时，首先可以查看Connectivity Ring Buffer中的LoginTimers类型错误来分析，如果想获得更详尽的信息，再通过抓包工具network monitor。

具体方法和语句可参考以下文章：

https://blogs.msdn.microsoft.com/apgcdsd/2011/11/20/ring-buffersql-server-2008/

http://ultrasql.blog.51cto.com/9591438/1583446

查询超时

对于查询超时，针对SQL Server 2012以下的版本，使用Profiler的TSQL_Duration模板的基础上，添加"Errors and Warnings"下的"Attention"，根据捕获到的Attention结合上下文去查找相应的语句；对于SQL Server 2012及以上版本，直接使用扩展事件监控sqlserver.attention事件，直接输出sql_text。

以下为XE脚本：

use tempdb   go    if exists (select * from sys.objects where name = 'sqlws_xev_attention')        drop view sqlws_xev_attention    go    create view sqlws_xev_attention as    with xevents (event_data)    as    (        select event.query('.') as event_data from             ((select cast (xest.target_data as xml) as target_data                    from sys.dm_xe_sessions as xes                    inner join sys.dm_xe_session_targets as xest on (xes.address = xest.event_session_address)                    where xes.name = 'sqlws_xevents_attention' and xest.target_name = 'ring_buffer') as td                cross apply target_data.nodes ('//event[@name="attention"]') as x (event))    )    select event_data.value ('(event/@name)[1]', 'varchar(max)') as event_name,        event_data.value ('(event/@timestamp)[1]', 'datetime') as event_timestamp,        event_data.value ('(event/data[@name="duration"]/value)[1]', 'bigint') as [duration],        event_data.value ('(event/data[@name="request_id"]/value)[1]', 'int') as [request_id],        event_data.value ('(event/action[@name="client_app_name"]/value)[1]', 'nvarchar(max)') as action_client_app_name,        event_data.value ('(event/action[@name="client_hostname"]/value)[1]', 'nvarchar(max)') as action_client_hostname,        event_data.value ('(event/action[@name="database_name"]/value)[1]', 'nvarchar(max)') as action_database_name,        event_data.value ('(event/action[@name="nt_username"]/value)[1]', 'nvarchar(max)') as action_nt_username,        event_data.value ('(event/action[@name="session_id"]/value)[1]', 'int') as action_session_id,        event_data.value ('(event/action[@name="sql_text"]/value)[1]', 'nvarchar(max)') as action_sql_text        from xevents    go    if exists (select * from sys.server_event_sessions where name = 'sqlws_xevents_attention')        drop event session sqlws_xevents_attention on server    go    create event session sqlws_xevents_attention on server        add event sqlserver.attention (action (sqlserver.client_app_name, sqlserver.client_hostname, sqlserver.database_name, sqlserver.nt_username, sqlserver.session_id, sqlserver.sql_text) where duration > 5000 )        add target package0.ring_buffer         with (event_retention_mode = ALLOW_SINGLE_EVENT_LOSS, memory_partition_mode = NONE)    go    /*    alter event session sqlws_xevents_attention on server state = start    go    --Execute your workload    with xevents (event_name)    as    (        select event.value ('(@name)[1]', 'varchar(max)') as event_name            from ((select cast (xest.target_data as xml) as target_data                    from sys.dm_xe_sessions as xes                    inner join sys.dm_xe_session_targets as xest on (xes.address = xest.event_session_address)                    where xes.name = 'sqlws_xevents_attention' and xest.target_name = 'ring_buffer') as td                cross apply target_data.nodes ('//event[@name="attention"]') as x (event))    )    select event_name, count(*) from xevents        group by event_name    go    select * from sqlws_xev_attention    go    alter event session sqlws_xevents_attention on server state = stop    go    */

调优建议

对于连接耗时，当然务必要找到具体原因，是网络问题还是验证问题；对于查询超时，多为语句性能问题导致，如阻塞、未使用合理的索引、输出数据量太大等原因。对于临时解决问题，可以在连接配置里、或在程序里的语句级参数属性调大配置值。当然应及时找出问题的根源并解决。