死锁和阻塞是数据库中最常见的问题,一般遇到的时候如何查找阻塞的源头:
首先查看 sys.sysprocesses 中blocked 情况,然后查看对应的lastwaitype and waitresource .
对于waitresource 主要有几种情况:
举个常用的例子:
(一)
Page:20:11:1635088
20:database Id
11:File Id
1635088 :Page Id
1 .首先找到数据库名字
select object_name(20)
2.找到数据库的文件名字
use DBName select * from sys.database_files where file_id =11
3. 通过page id 找到具体的对象:
打开DBCC 3604 开关,然后运行DBCC Page (databaseName,fileId,pageId,dumStyle)
DBCC TRACEON(3604) DBCC Page (DBNAME,11,1635088 ,2)
我们会看到如下的数据:
ge @0x000000A93DC34000
m_pageId = (11:1635088) m_headerVersion = 1 m_type = 1
m_typeFlagBits = 0x0 m_level = 0 m_flagBits = 0xa200
m_objId (AllocUnitId.idObj) = 13777 m_indexId (AllocUnitId.idInd) = 256
Metadata: AllocUnitId = 72057594940817408
Metadata: PartitionId = 72057594859618304 Metadata: IndexId = 1
Metadata: ObjectId = 727829805 m_prevPage = (12:691363) m_nextPage = (11:1635089)
pminlen = 22 m_slotCnt = 99 m_freeCnt = 4
m_freeData = 7990 m_reservedCnt = 0 m_lsn = (2091562:262743:114)
m_xactReserved = 0 m_xdesId = (0:0) m_ghostRecCnt = 0
m_tornBits = 816587892 DB Frag ID = 1
...
SELECT sc.name as schema_name, so.name as object_name, si.name as index_name FROM sys.objects as so JOIN sys.indexes as si on so.object_id=si.object_id JOIN sys.schemas AS sc on so.schema_id=sc.schema_id WHERE so.object_id = 727829805 and si.index_id = 1; GO
在SQLserver2014的版本上,我们可以利用无文档的系统视图 sys.dm_db_database_page_allocations ,但是这个查询是一个非常消耗性能的操作。
在看到对象之后我们可以继续查找锁定的数据,同样的这个操作也是消耗性能的操作 (sqlserver2008版本以上) ,如下:
use DBName SELECT sys.fn_PhysLocFormatter (%%physloc%%), * FROM dbo.TableName (NOLOCK) WHERE sys.fn_PhysLocFormatter (%%physloc%%) like '(1:1635088%' GO
(二)
对于KEY: 6:72057594041991168 (ce52f92a058c)
database =6;
hotbt_id=72057594041991168
hash value=ce52f92a058c
同样的我们通过如下的脚本获取对象
--get database name select db_name(6) ; --get object name and index name use databasename; SELECT sc.name as schema_name, so.name as object_name, si.name as index_name FROM sys.partitions AS p JOIN sys.objects as so on p.object_id=so.object_id JOIN sys.indexes as si on p.index_id=si.index_id and p.object_id=si.object_id JOIN sys.schemas AS sc on so.schema_id=sc.schema_id WHERE hobt_id = 72057594041991168; GO
对于最后的hash value ,我们也有函数找到对应的行数据
SELECT * FROM dbo.TableName(NOLOCK) WHERE %%lockres%% = '(ce52f92a058c)'; GO