sqlserver 数据库阻塞和死锁

参考原文：http://blog.csdn.net/ha196200/article/details/44985597

(1) 数据库阻塞： 假设第一个连接T1占有且没有释放资源，第二个连接T2请求同一资源（表tb）时需要等待，若T1没有提交或回滚，T2将持续等待，导致阻塞发生。

第一个连接：

begin tran
  update tb set num=2 where id=1

第二个连接：

begin tran
  update tb set num=2 where id=1
commit tran

(2)  数据库死锁： 第一个连接占有资源没有释放，准备获取第二个连接所占用的资源，而第二个连接占有资源没有释放，准备获取第一个连接所占用的资源。这种互相占有对方需要获取的资源的现象叫做死锁。对于死锁，数据库处理方法：牺牲一个连接，保证另外一个连接成功执行。

第一个连接：

begin
  update t1 set num=2 where id=1; --先修改t1
  waitfor delay '00:00:20'        --等待20s
  update t2 set num=2 where id=1; --再修改t2
end

第二个连接：

begin
  update t2 set num=2 where id=1; --先修改t1
  waitfor delay '00:00:20'        --等待20s
  update t1 set num=2 where id=1; --再修改t2
end

1. Activity Monitor

         

2. EXEC sp_who2

3. 检查阻塞

 

SELECT  R.session_id AS BlockedSessionID ,
        S.session_id AS BlockingSessionID ,
        Q1.text AS BlockedSession_TSQL ,
        Q2.text AS BlockingSession_TSQL ,
        C1.most_recent_sql_handle AS BlockedSession_SQLHandle ,
        C2.most_recent_sql_handle AS BlockingSession_SQLHandle ,
        S.original_login_name AS BlockingSession_LoginName ,
        S.program_name AS BlockingSession_ApplicationName ,
        S.host_name AS BlockingSession_HostName
FROM    sys.dm_exec_requests AS R
        INNER JOIN sys.dm_exec_sessions AS S ON R.blocking_session_id = S.session_id
        INNER JOIN sys.dm_exec_connections AS C1 ON R.session_id = C1.most_recent_session_id
        INNER JOIN sys.dm_exec_connections AS C2 ON S.session_id = C2.most_recent_session_id
        CROSS APPLY sys.dm_exec_sql_text(C1.most_recent_sql_handle) AS Q1
        CROSS APPLY sys.dm_exec_sql_text(C2.most_recent_sql_handle) AS Q2

 4. 检查死锁

sys.sysprocesses 系统表是一个很重要的系统视图，主要用来定位与解决Sql Server的阻塞和死锁。如 SPID130的blocked 字段值为158，而SPID158 的 blocked 为0，就可以得出结论：130 被 158 阻塞住了。如果你发现一个连接的 blocked 字段的值等于它自己，那说明这个连接正在做磁盘读写，它要等自己的 I/O 做完。

select spid, blocked, loginame, last_batch, status, cmd, hostname, program_name
from sysprocesses
where blocked <>0 or spid in(select blocked from sysprocesses where blocked<>0) 

 5. 检查死锁

select * from sys.dm_tran_locks where request_status='WAIT'

 6. 自动监测

CREATE procedure sp_who_lock
as
begin
  declare @spid int
  declare @blk int
  declare @count int
  declare @index int
  declare @lock tinyint
  set @lock=0
  create table #temp_who_lock
  (
    id int identity(1,1),
    spid int,
    blk int
  )
  if @@error<>0 return @@error
  insert into #temp_who_lock(spid,blk)
  select 0 ,blocked from (select * from master..sysprocesses where blocked>0)a
  where not exists(select * from  master..sysprocesses where a.blocked =spid and blocked>0)
  union select spid,blocked from  master..sysprocesses where blocked>0
  if @@error<>0 return @@error
  select @count=count(*),@index=1 from #temp_who_lock
  if @@error<>0 return @@error
  if @count=0
  begin
    select '没有阻塞和死锁信息'
    return 0
  end
  while @index<=@count
  begin
    if exists(select 1 from #temp_who_lock a where id>@index and exists(select 1 from #temp_who_lock where id<=@index and a.blk=spid))
    begin
      set @lock=1
      select @spid=spid,@blk=blk from #temp_who_lock where id=@index
      select '引起数据库死锁的是: '+ CAST(@spid AS VARCHAR(10)) + '进程号,其执行的SQL语法如下'
      select  @spid, @blk
      dbcc inputbuffer(@spid)
      dbcc inputbuffer(@blk)
    end
    set @index=@index+1
 end
 if @lock=0
 begin
  set @index=1
  while @index<=@count
  begin
    select @spid=spid,@blk=blk from #temp_who_lock where id=@index
    if @spid=0
      select '引起阻塞的是:'+cast(@blk as varchar(10))+ '进程号,其执行的SQL语法如下'
    else
      select '进程号SPID：'+ CAST(@spid AS VARCHAR(10))+ '被' + '进程号SPID：'+ CAST(@blk AS VARCHAR(10)) +'阻塞,其当前进程执行的SQL语法如下'
    dbcc inputbuffer(@spid)
    dbcc inputbuffer(@blk)
    set @index=@index+1
 end
end
drop table #temp_who_lock
return 0
end  

查看数据库表修改记录

SELECT [Transaction ID],Operation,Context,AllocUnitName
FROM fn_dblog(NULL, NULL) 

查看数据库字段修改记录

SELECT
    表名=CASE WHEN C.column_id=1 THEN O.name ELSE N'' END,
    表说明=ISNULL(CASE WHEN C.column_id=1 THEN PTB.[value] END,N''),
    字段序号=C.column_id,
    字段名=C.name,
    主键=ISNULL(IDX.PrimaryKey,N''),
    标识=CASE WHEN C.is_identity=1 THEN N'√'ELSE N'' END,
    计算列=CASE WHEN C.is_computed=1 THEN N'√'ELSE N'' END,
    类型=T.name,
    长度=C.max_length,
    精度=C.precision,
    小数位数=C.scale,
    允许空=CASE WHEN C.is_nullable=1 THEN N'√'ELSE N'' END,
    默认值=ISNULL(D.definition,N''),
    字段说明=ISNULL(PFD.[value],N''),
    索引名=ISNULL(IDX.IndexName,N''),
    索引排序=ISNULL(IDX.Sort,N''),
    创建时间=O.Create_Date,
    修改时间=O.Modify_date
FROM sys.columns C
    INNER JOIN sys.objects O
        ON C.[object_id]=O.[object_id]
            AND O.type='U'
            AND O.is_ms_shipped=0
    INNER JOIN sys.types T
        ON C.user_type_id=T.user_type_id
    LEFT JOIN sys.default_constraints D
        ON C.[object_id]=D.parent_object_id
            AND C.column_id=D.parent_column_id
            AND C.default_object_id=D.[object_id]
LEFT JOIN sys.extended_properties PFD
        ON PFD.class=1
            AND C.[object_id]=PFD.major_id
            AND C.column_id=PFD.minor_id
--             AND PFD.name='Caption'  -- 字段说明对应的描述名称(一个字段可以添加多个不同name的描述)
    LEFT JOIN sys.extended_properties PTB
        ON PTB.class=1
            AND PTB.minor_id=0
            AND C.[object_id]=PTB.major_id
--             AND PFD.name='Caption'  -- 表说明对应的描述名称(一个表可以添加多个不同name的描述)
    LEFT JOIN                       -- 索引及主键信息
    (
        SELECT
            IDXC.[object_id],
            IDXC.column_id,
            Sort=CASE INDEXKEY_PROPERTY(IDXC.[object_id],IDXC.index_id,IDXC.index_column_id,'IsDescending')
                WHEN 1 THEN 'DESC' WHEN 0 THEN 'ASC' ELSE '' END,
            PrimaryKey=CASE WHEN IDX.is_primary_key=1 THEN N'√'ELSE N'' END,
            IndexName=IDX.Name
        FROM sys.indexes IDX
        INNER JOIN sys.index_columns IDXC
ON IDX.[object_id]=IDXC.[object_id]
                AND IDX.index_id=IDXC.index_id
        LEFT JOIN sys.key_constraints KC
            ON IDX.[object_id]=KC.[parent_object_id]
                AND IDX.index_id=KC.unique_index_id
        INNER JOIN  -- 对于一个列包含多个索引的情况,只显示第1个索引信息
        (
            SELECT [object_id], Column_id, index_id=MIN(index_id)
            FROM sys.index_columns
            GROUP BY [object_id], Column_id
        ) IDXCUQ
            ON IDXC.[object_id]=IDXCUQ.[object_id]
                AND IDXC.Column_id=IDXCUQ.Column_id
                AND IDXC.index_id=IDXCUQ.index_id
    ) IDX
        ON C.[object_id]=IDX.[object_id]
            AND C.column_id=IDX.column_id
--WHERE O.name = 'viewvoutpage'
    -- 如果只查询指定表,加上此条件
ORDER BY O.name,C.column_id