连接超时
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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。
