零、 常见等待类型及含义
表格内容来自 Understand and resolve blocking problems - SQL Server | Microsoft Learn
Resource | Format | Example |
Table | DatabaseID:ObjectID:IndexID | TAB: 5:261575970:1 In this case, database ID 5 is the pubs sample database and object ID 261575970 is the titles table and 1 is the clustered index. |
Page | DatabaseID:FileID:PageID | PAGE: 5:1:104 For example: |
Key | DatabaseID:Hobt_id (Hash value for index key) | KEY: 5:72057594044284928 (3300a4f361aa) In this case, database ID 5 is Pubs, Hobt_ID 72057594044284928 corresponds to non clustered index_id 2 for object id 261575970 (titles table). Use the sys.partitions catalog view to associate the hobt_id to a particular index id and object id. There is no way to unhash the index key hash to a specific index key value. |
Row | DatabaseID:FileID:PageID:Slot(row) | RID: 5:1:104:3 In this case, database ID 5 is pubs, file ID 1 is the primary data file, page 104 is a page belonging to the titles table, and slot 3 indicates the row's position on the page. |
Compile | DatabaseID:FileID:PageID:Slot(row) | RID: 5:1:104:3 In this case, database ID 5 is pubs, file ID 1 is the primary data file, page 104 is a page belonging to the titles table, and slot 3 indicates the row's position on the page. |
下面来看常见waitresource的具体分析
一、 waitresource=PAGE
waitresource=PAGE: 6:3:70133 = Database_Id : File_Id : Page_Number
- database_id = 6
- file_id = 3
- Page_Number = 70133
有了这个信息，首先可以找到阻塞发生的DB，也可以去找文件名，不过用处不大。
SELECT name FROM sys.databases WHERE database_id=6;
SELECT name,physical_name FROM sys.database_files WHERE file_id = 3;这里最有用的是页号，有了它就能通过DBCC定位到它是哪个表的页，是数据页还是索引页还是特殊类型的页。
DBCC TRACEON (3604);
GO
/* DBCC PAGE (DatabaseName, FileNumber, PageNumber, DumpStyle)*/
DBCC PAGE ('WideWorldImporters',3,70133,2);
GO
可以看到它是个索引，再继续找具体对象名
USE WideWorldImporters;
GO
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 = 94623380
and si.index_id = 1;可以查到它是Sales.OrderLines表上的PK_Sales_OrderLines索引。
能查到页中被阻塞的是哪些行吗，其实也可以。可以使用未公开的 sys.fn_PhysLocFormatter (%%physloc%%) 函数，它会返回页中对应的记录，2008及以上版本可用，但要注意即使是小表执行时间可能也很长。
SELECT sys.fn_PhysLocFormatter (%%physloc%%), * FROM Sales.OrderLines (NOLOCK) WHERE sys.fn_PhysLocFormatter (%%physloc%%) like '(3:70133%';
当然，如果生产环境的表变化非常频繁，也无法保证这些行就是之前阻塞时的行，仅作为参考。
另外还有一个方法，DBCC PAGE参数为3时，可以输出缓冲区的标题、可读形式的页头数据、每行记录的16进制数据（每行后跟分别列出的它的列值），也可以看到相应数据。
DBCC TRACEON (3604);
GO
/* DBCC PAGE (DatabaseName, FileNumber, PageNumber, DumpStyle)*/
DBCC PAGE ('WideWorldImporters',3,70133,3);
GO二、 waitresource=KEY
KEY: 6:72057594041991168 (ce52f92a058c) = Database_Id, HOBT_Id (magic hash value)
- database_id = 6
- hobt_id = 72057594041991168
- magic hash value = (ce52f92a058c)
DB名的找法跟前面一样，主要是hobt_id能定位到对应key名
USE WideWorldImporters;
GO
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;可以看到是 Application.Countries 表的 PK_Application_Countries 索引
magic hash value可以解码出%%lockres%%，用于定位被阻塞的行（缺点也跟前面类似）
SELECT * FROM Application.Countries (NOLOCK) WHERE %%lockres%% = '(ce52f92a058c)';
三、 waitresource=OBJECT
waitresource="OBJECT: 6:12347015633:1 "=Database_Id:Object_Id:PageNumber
第三个字段是PageNumber，通过它可以还原阻塞发生的现场情况，真正阻塞的临界资源是一个Page。
四、 waitresource=TAB
waitresource="TAB: 5:261575970:1"=DatabaseID:ObjectID:IndexID
在阻塞发生时，数据库应该正在做全表扫描操作，阻塞发生在一个表或索引上，查询在请求资源时把整个表都锁定了。
参考
Decoding Key and Page WaitResource for Deadlocks and Blocking - littlekendra.com
Understand and resolve blocking problems - SQL Server | Microsoft Learn
《SQL Server 2012王者归来——基础、安全、开发及性能优化》
