SQLServer 通过DMV实现低影响的自动监控和历史场景追溯

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一. 背景：

我们管理和维护的数据库系统基本都是7*24小时运转的，运转时会出现什么情况谁都无法估计，往往一个平时运行很正常的系统，某天晚上突然就抽风了，而此刻并没有系统负责人在旁边，当值班同事的电话打到正在酣睡的DBA手机上时，DBA不得不朦朦胧胧的，条件反射要上数据库看看；要在家里连到公司的内外一般都需要DBA通知运维人员（也可能是个在做梦的哥们）先给自己开个VPN（某些管控严格的公司还需要DBA打车去公司才能处理），然后通过一大堆的验证才通过慢如蜗牛（往往也和此刻的心态有关）的网络，远程连接到了公司内网出问题的数据库上，此刻DBA才开始真正开始排查起问题来；如果说等待DBA登录到问题数据库上，问题依然在出现，那还算好，可以很快找到问题并处理，但是往往这种抽风的现象是短暂的，可能持续几分钟后，系统又恢复了正常，等到DBA"跑山涉水，翻山越岭" 的好不容易登录到数据库上检查时，数据库里的进程、锁、日志一起都正常，系统运行的很Hai；于是第二天上班时老大们问起昨天晚上事故的原因时，DBA只能凭空猜测，可能是网络、数据库阻塞、抑或是程序方面的问题吧......，此刻不同部门的人都猜是其他部门管理的东西出了问题，于是大家都把手头上的数据、监控图拿出来，证明自己这里是没有问题的；如果监控网络和系统的图和APP的Log都没用出现啥问题（说实话监控也不一定准确的），那就基本要把问题推到数据库身上了（DBA往往成为炮灰）。

数据库有没有出问题，如果出了问题又是啥问题呢？windows Log和DB Log都没异常，如果我们没有把Profile持续的开启（基于性能的考虑，一般都不会持续开启），就很难说清楚在系统出问题时数据库究竟有没有出问题，出了问题又是因为什么原因引起的；如果说此类问题出现了一次，就消失了，那还算好，成为一个无头案，悲剧的是这类问题无规律，反复的出现，如果DBA不能找出问题的原因，也不能证明数据库当时是正常的话，估计在公司里面就没用立足之地了。

二 . 对策：

其实对这种灵异的系统抽风事件，有两种比较好的解决方案：

1. 开启Trace 跟踪，就是数据库的Profile功能，这个还可以结合windows的性能计数器一同使用，能够直观的了解到特殊时间点上运行了什么语句，资源消耗情况是怎样的；不过这个方法比较消耗系统的资源，对访问压力比较大的数据库需要慎重；

2. 收集数据库DMV当时的情况，使得DBA在故障时间过后，还能通过这些数据了解到事故发生时，数据库里面运行的语句，以及锁和资源的情况；这种方法只是访问系统性能视图，对数据库其他业务影响比较小，也是我接下来要介绍的方案。

三. 实施方案：

思路：根据数据库中某些动态指标，触发收集DMV的过程，必要时发送报警邮件

1. 创建存储系统性能视图的表：

--创建四个记录表
USE [master]
GO

/****** Object: Table [dbo].[dc_block_info]    Script Date: 05/23/2011 11:35:48 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[dc_block_info](
    [spid] [smallint] NULL,
    [status] [nchar](30) NULL,
    [SQLBuffer] [nvarchar](max) NULL,
    [hostname] [nchar](128) NULL,
    [BlkBy] [varchar](10) NULL,
    [BlockedSQLBuffer] [nvarchar](max) NULL,
    [LoginName] [varchar](100) NULL,
    [DBName] [varchar](50) NULL,
    [CPUTime] [int] NULL,
    [DiskIO] [int] NULL,
    [LastBatch] [datetime] NULL,
    [program_name] [nchar](128) NULL,
    [Command] [varchar](100) NULL,
    [batch_id] [int] NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

USE [master]
GO

/****** Object: Table [dbo].[dc_Blocked_Resource_Info]    Script Date: 05/23/2011 11:35:48 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[dc_Blocked_Resource_Info](
    [spid] [smallint] NULL,
    [dbid] [smallint] NOT NULL,
    [ObjId] [int] NOT NULL,
    [IndId] [smallint] NOT NULL,
    [Type] [nvarchar](4) NULL,
    [Resource] [nvarchar](32) NULL,
    [Mode] [nvarchar](8) NULL,
    [Status] [nvarchar](5) NULL,
    [batch_id] [int] NULL
) ON [PRIMARY]

GO

USE [master]
GO

/****** Object: Table [dbo].[dc_info_BlockedInfo]    Script Date: 05/23/2011 11:35:48 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[dc_info_BlockedInfo](
    [batch_id] [int] NULL,
    [lock_type] [varchar](100) NULL,
    [database_name] [varchar](20) NULL,
    [blk_object] [varchar](100) NULL,
    [lock_req] [varchar](100) NULL,
    [waiter_sid] [int] NULL,
    [wait_time] [int] NULL,
    [waiter_batch] [varchar](max) NULL,
    [waiter_stmt] [varchar](max) NULL,
    [blocker_sid] [int] NULL,
    [blocker_stmt] [varchar](max) NULL,
    [create_date] [datetime] NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

USE [master]
GO

/****** Object: Table [dbo].[dc_info_SessionConn]    Script Date: 05/23/2011 11:35:48 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[dc_info_SessionConn](
    [batch_id] [int] NULL,
    [session_id] [int] NULL,
    [blocking_session_id] [int] NULL,
    [textdata] [varchar](max) NULL,
    [login_name] [varchar](30) NULL,
    [host_name] [varchar](100) NULL,
    [database_name] [varchar](30) NULL,
    [program_name] [varchar](200) NULL,
    [command] [varchar](100) NULL,
    [status] [varchar](20) NULL,
    [cpu_time] [int] NULL,
    [memory_usage_kb] [int] NULL,
    [reads] [int] NULL,
    [writes] [int] NULL,
   [transaction_isolation_level] [int] NULL,
    [connect_time] [datetime] NULL,
    [last_read] [datetime] NULL,
    [last_write] [datetime] NULL,
    [net_transport] [varchar](20) NULL,
    [client_net_address] [varchar](30) NULL,
    [client_tcp_port] [int] NULL,
    [local_tcp_port] [int] NULL,
    [start_time] [datetime] NULL,
    [wait_time] [int] NULL,
    [wait_type] [varchar](100) NULL,
    [last_wait_type] [varchar](100) NULL,
    [wait_resource] [varchar](1000) NULL,
    [open_transaction_count] [int] NULL,
    [create_date] [datetime] NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

2. 定义性能收集的存储过程：

USE [master]
GO

--数据库的阻塞和锁信息，该SP可以记录session中显示不出的信息
create procedure [dbo].[usp_blocker_info](@batch_id int)

as

begin

set nocount on

declare @spid smallint,@blocked smallint

declare @c_SQL nvarchar(4000),@b_SQL nvarchar(4000)

declare @id int

--保存Sysprocesses 的内容

create table #Temp(spid smallint,status nchar(30),hostname nchar(128),program_name nchar(128)

   ,cmd nchar(16),cpu int,physical_io int,blocked smallint,dbid smallint

   ,loginame nchar(128),last_batch datetime

   ,SQLBuffer nvarchar(4000),BlockedSQLBuffer nvarchar(4000))


--保存DBCC InputBuffer 的结果

create table #Temp1(id int identity(1,1),eventtype varchar(20),parameters int,eventinfo nvarchar(4000))

create table #Temp_b(id int identity(1,1),eventtype varchar(20),parameters int,eventinfo nvarchar(4000))

select * into #Temp2

from master..sysprocesses (nolock)


--保存被阻塞的进程信息

insert into #Temp(spid ,status ,hostname ,program_name ,cmd ,cpu ,physical_io ,blocked ,dbid

   ,loginame ,last_batch )

SELECT spid ,status ,hostname ,program_name ,cmd ,cpu ,physical_io ,blocked ,dbid

     ,convert(sysname, rtrim(loginame)) ,last_batch

   from #Temp2

   where blocked > 0

--保存阻塞的源头

insert into #Temp(spid ,status ,hostname ,program_name ,cmd ,cpu ,physical_io ,blocked ,dbid

   ,loginame ,last_batch )

SELECT spid ,status ,hostname ,program_name ,cmd ,cpu ,physical_io ,blocked ,dbid

     ,convert(sysname, rtrim(loginame)) ,last_batch

   from #Temp2

   where spid in (select blocked from #Temp)

    and spid not in (select spid from #Temp)


select @spid = min(spid) from #Temp


while @spid is not null

begin

set @c_SQL ='dbcc inputbuffer(' + convert(varchar(5), @spid) + ')'

select @blocked= isnull(blocked,0) from #Temp where spid=@spid

if(@blocked<>0)
   begin
    set @b_SQL ='dbcc inputbuffer(' + convert(varchar(5), @blocked) + ')'
    insert into #Temp_b
        exec (@b_SQL)

   select @id = @@identity

   update #Temp

   set BlockedSQLBuffer = #Temp_b.eventinfo

   from #Temp,#Temp_b

   where #Temp_b.id = @id

    and #Temp.blocked = @blocked
   end


insert into #Temp1

   exec (@c_SQL)


select @id = @@identity


   update #Temp

    set SQLBuffer = #Temp1.eventinfo

   from #Temp,#Temp1

   where #Temp1.id = @id

    and #Temp.spid = @spid


select @spid = min(spid) from #Temp where spid > @spid

end


insert into dc_block_info(batch_id,spid,status,SQLBuffer,hostname,BlkBy,BlockedSQLBuffer,LoginName,DBName,
CPUTime,DiskIO,LastBatch,program_name,Command)

SELECT @batch_id,convert(char(5),spid) SPID,CASE lower(status) When 'sleeping' Then lower(status) Else upper(status) END Status

   ,SQLBuffer

   , CASE hostname When Null Then ' .' When ' ' Then ' .' Else hostname END HostName

   ,CASE isnull(convert(char(5),blocked),'0') When '0' Then ' .'

                       Else isnull(convert(char(5),blocked),'0') END BlkBy,BlockedSQLBuffer

   ,loginame Login

   ,db_name(dbid) DBName,convert(varchar,cpu) CPUTime

   ,convert(varchar,physical_io) DiskIO,Last_Batch LastBatch

   ,program_name ProgramName, cmd Command

from #Temp

order by BlkBy, spid


set nocount off

end

Go

USE [master]
GO

--预警SP
CREATE proc [dbo].[RecodeAndAlertInfo]
as
begin
declare @banch_id int
select @banch_id=isnull(MAX(batch_id),0)+1 from dc_info_SessionConn

--记录当前所有会话信息
insert into dc_info_SessionConn
SELECT @banch_id,S.session_id, R.blocking_session_id,
current_execute_sql = SUBSTRING(T.text,
    R.statement_start_offset / 2 + 1,
    CASE
     WHEN statement_end_offset = -1 THEN LEN(T.text)
     ELSE (R.statement_end_offset - statement_start_offset) / 2+1
    END),
S.login_name,S.host_name,databaseName=DB_NAME(R.database_id),S.program_name,R.command,
S.status,S.cpu_time, memory_usage_kb = S.memory_usage * 8, S.reads, S.writes,
S.transaction_isolation_level,C.connect_time, C.last_read, C.last_write,
C.net_transport, C.client_net_address, C.client_tcp_port, C.local_tcp_port,
R.start_time, R.wait_time, R.wait_type, R.last_wait_type, R.wait_resource,
R.open_transaction_count,GETDATE()
FROM sys.dm_exec_sessions S
LEFT JOIN sys.dm_exec_connections C
ON S.session_id = C.session_id
LEFT JOIN sys.dm_exec_requests R
ON S.session_id = R.session_id
   AND C.connection_id = R.connection_id
OUTER APPLY sys.dm_exec_sql_text(R.sql_handle) T
WHERE S.is_user_process = 1 -- 如果不限制此条件，则查询所有进程（系统和用户进程）
AND command is not null


--记录当前阻塞信息
insert into dc_info_BlockedInfo
select @banch_id,t1.resource_type as [lock type] ,db_name(resource_database_id) as [database]
,t1.resource_associated_entity_id as [blk object]
,t1.request_mode as [lock req]                          -- lock requested
,t1.request_session_id as [waiter sid]                      -- spid of waiter
,t2.wait_duration_ms as [wait time]
,(select text from sys.dm_exec_requests as r                  --- get sql for waiter
cross apply sys.dm_exec_sql_text(r.sql_handle)
where r.session_id = t1.request_session_id) as waiter_batch
,(select substring(qt.text,r.statement_start_offset/2,
(case when r.statement_end_offset = -1 then len(convert(nvarchar(max), qt.text)) *2
else r.statement_end_offset end - r.statement_start_offset)/2)
from sys.dm_exec_requests as r
cross apply sys.dm_exec_sql_text(r.sql_handle) as qt
where r.session_id = t1.request_session_id) as waiter_stmt    --- statement executing now
,t2.blocking_session_id as [blocker sid]                --- spid of blocker
,(select text from sys.sysprocesses as p                       --- get sql for blocker
cross apply sys.dm_exec_sql_text(p.sql_handle)
where p.spid = t2.blocking_session_id) as blocker_stmt,getdate()
from sys.dm_tran_locks as t1, sys.dm_os_waiting_tasks as t2
where t1.lock_owner_address = t2.resource_address


--记录资源信息
insert into dc_Blocked_Resource_Info
select convert (smallint, req_spid) As spid,
  rsc_dbid As dbid,
rsc_objid As ObjId,
rsc_indid As IndId,
substring (v.name, 1, 4) As Type,
substring (rsc_text, 1, 32) as Resource,
substring (u.name, 1, 8) As Mode,
substring (x.name, 1, 5) As Status ,@banch_id
from master.dbo.syslockinfo,
master.dbo.spt_values v,
master.dbo.spt_values x,
master.dbo.spt_values u
where   master.dbo.syslockinfo.rsc_type = v.number
   and v.type = 'LR'
   and master.dbo.syslockinfo.req_status = x.number
   and x.type = 'LS'
   and master.dbo.syslockinfo.req_mode + 1 = u.number
   and u.type = 'L'
and substring (x.name, 1, 5) = 'WAIT'
order by spid

exec usp_blocker_info @banch_id

end

GO

3. 创建信息收集和邮件报警的SP：

说明：

SP定义了一个邮件发送的过程，需要先配置好数据库的邮件发送（google一下很多的）；

SP需要做到JOB里面，一分钟运行一次收集信息；

SP收集信息时的条件（不同的系统触发条件不一样）：

a. 用户链接数大于550，活动链接数大于40；

b. 阻塞进程比率大于10%；

USE [master]
GO
--创建触发监控条件，并发邮件
CREATE proc [dbo].[ConAlert]
as
begin
DECLARE @conn float ,@activeconn float ,@blockedcount float,@spidcount float,@spidblocked float ,@count int
DECLARE @body NVARCHAR(MAX),@subject nvarchar(200)

-- User Connections
Select @conn=ISNULL(cntr_value,0) from sys.dm_os_performance_counters with(nolock)
where counter_name='User Connections'

if @conn>=550 --根据用户链接数来收集信息和触发报警
   begin
     --active requests
     Select @activeconn=isnull(SUM(cntr_value),0) from sys.dm_os_performance_counters with(nolock)
       where counter_name = 'Active requests'
       group by counter_name

    set @count=1

    if @activeconn>=40 --根据活动链接数来判断
     begin
       while 1=1 --循环收集信息
        begin
            exec RecodeAndAlertInfo

           if(@count%5=0) --连续次就发邮件
             begin
               set @subject='Server:'+@@SERVERNAME+' Connections Alert'
               SET @body ='Server:'+@@SERVERNAME+CHAR(13)+'; UserConnections:'+cast(@conn as varchar)+CHAR(13)+'; ActiveRequests:'+ cast(@activeconn as varchar)
               EXEC msdb.dbo.sp_send_dbmail
                @recipients =N'Ken@xxx.com;itmon@xxx.com',
                @body = @body,
                @body_format ='TEXT',
                @subject =@subject,
                @profile_name ='dba_profile' --需要配置该模板
             end

             Select @activeconn=isnull(SUM(cntr_value),0) from sys.dm_os_performance_counters with(nolock)
               where counter_name = 'Active requests'
               group by counter_name

             if @activeconn>=40
                 waitfor delay '00:00:05'
             else
                  break;

             if @count>50
                   break;

           set @count=@count+1;
       end
   end
   end
else --根据Blocked 百分比来收集信息和触发报警
   begin
     select @spidcount=count(0) from sys.sysprocesses with(nolock) where spid>50
     select @blockedcount=count(0) from sys.sysprocesses with(nolock) where spid>50 and blocked<>0
     --计算百分比
     set @spidblocked=@blockedcount/@spidcount
     set @count=1

     if(@spidblocked>=0.1) --10%时，记录信息
      begin
       while 1=1 --循环收集信息
        begin
            exec RecodeAndAlertInfo

           if(@count%5=0 or @spidblocked>=0.15) --连续5次阻塞比率大于10%或者阻塞比率大于等于15%时，记录信息并发生报警邮件
             begin
                set @subject='Server:'+@@SERVERNAME+' Blocked Alert'
                SET @body ='Server:'+@@SERVERNAME+CHAR(13)+'; BlockedCount:'+cast(@blockedcount as varchar)+CHAR(13)+'; SPIDCount:'+ cast(@spidcount as varchar)
                EXEC msdb.dbo.sp_send_dbmail
                @recipients =N'Ken@xxx.com',
                @body = @body,
                @body_format ='TEXT',
                @subject =@subject,
                @profile_name ='dba_profile'
             end

             select @spidcount=count(0) from sys.sysprocesses with(nolock) where spid>50
             select @blockedcount=count(0) from sys.sysprocesses with(nolock) where spid>50 and blocked<>0
             set @spidblocked=@blockedcount/@spidcount

             if @spidblocked>=0.1
                 waitfor delay '00:00:05'
             else
                  break;

             if @count>50
                   break;

           set @count=@count+1;
       end
      end
   end
end

4. 查看信息：

USE [master]
GO
--通过以下查询来分析信息
declare @batch_id int
select @batch_id=isnull(MAX(@batch_id),1) from dc_info_SessionConn

select * from dc_info_SessionConn where batch_id=@batch_id
select * from dc_info_BlockedInfo where batch_id=@batch_id
select * from dc_block_info where batch_id=@batch_id
select * from dc_Blocked_Resource_Info where batch_id=@batch_id

有了这些阻塞、进程和资源的信息，我们就可以了解系统出问题时，数据库是否出现异常，以及数据库异常时都有些什么语句在系统中运行，它们是否造成了大量的阻塞或消耗了大量的资源；这样DBA就方便定位问题了。