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Tuesday, June 12, 2012

Locking and Blocking Scripts in SQL Server 2000 vs SQL Server 2005

SQL Server 2000
In SQL Server 2000 the main stored procedure to find out which locks were issued was sp_lock. Typically this command was followed by sp_who2.In order to find out more information about the spid in terms of the user, host name, application, CPU and memory utilization either DBCC INPUTBUFFER or fn_get_sql was issued to find out exactly what code was being issued.If you ar eunable to find the required result then you might look into master.dbo.syslockinfo table and/or the master.dbo.sysprocesses table, although this was not always the recommended approach.


SQL Server 2000 - Locking Related Objects
ID
Object
Example
1
sp_lock - System stored procedure to identify all of the locks issued across the SQL Server instance
EXEC master.dbo.sp_lock
GO
2
sp_who and sp_who2 - System stored procedure to identify all of the processes across the SQL Server instance
EXEC master.dbo.sp_who2
GO
3
master.dbo.syslockinfo - System table with the locks issued across the SQL Server instance
SELECT req_spid AS 'spid',
DB_NAME(rsc_dbid) AS 'Database',
OBJECT_NAME(rsc_objid) AS 'Name',
rsc_indid AS 'Index',
rsc_text AS 'Description',
ResourceType = CASE WHEN rsc_type = 1 THEN 'NULL Resource'
WHEN rsc_type = 2 THEN 'Database'
WHEN rsc_type = 3 THEN 'File'
WHEN rsc_type = 4 THEN 'Index'
WHEN rsc_type = 5 THEN 'Table'
WHEN rsc_type = 6 THEN 'Page'
WHEN rsc_type = 7 THEN 'Key'
WHEN rsc_type = 8 THEN 'Extent'
WHEN rsc_type = 9 THEN 'RID (Row ID)'
WHEN rsc_type = 10 THEN 'Application'
ELSE 'Unknown'
END,
Status = CASE WHEN req_status = 1 THEN 'Granted'
WHEN req_status = 2 THEN 'Converting'
WHEN req_status = 3 THEN 'Waiting'
ELSE 'Unknown'
END,
OwnerType =
CASE WHEN req_ownertype = 1 THEN 'Transaction'
WHEN req_ownertype = 2 THEN 'Cursor'
WHEN req_ownertype = 3 THEN 'Session'
WHEN req_ownertype = 4 THEN 'ExSession'
ELSE 'Unknown'
END,
LockRequestMode =
CASE WHEN req_mode = 0 THEN 'No access '
WHEN req_mode = 1 THEN 'Sch-S (Schema stability)'
WHEN req_mode = 2 THEN 'Sch-M (Schema modification)'
WHEN req_mode = 3 THEN 'S (Shared)'
WHEN req_mode = 4 THEN 'U (Update)'
WHEN req_mode = 5 THEN 'X (Exclusive)'
WHEN req_mode = 6 THEN 'IS (Intent Shared)'
WHEN req_mode = 7 THEN 'IU (Intent Update)'
WHEN req_mode = 8 THEN 'IX (Intent Exclusive)'
WHEN req_mode = 9 THEN 'SIU (Shared Intent Update)'
WHEN req_mode = 10 THEN 'SIX (Shared Intent Exclusive)'
WHEN req_mode = 11 THEN 'UIX (Update Intent Exclusive)'
WHEN req_mode = 12 THEN 'BU. (Bulk operations)'
WHEN req_mode = 13 THEN 'RangeS_S'
WHEN req_mode = 14 THEN 'RangeS_U'
WHEN req_mode = 15 THEN 'RangeI_N'
WHEN req_mode = 16 THEN 'RangeI_S'
WHEN req_mode = 17 THEN 'RangeI_U'
WHEN req_mode = 18 THEN 'RangeI_X'
WHEN req_mode = 19 THEN 'RangeX_S'
WHEN req_mode = 20 THEN 'RangeX_U'
WHEN req_mode = 21 THEN 'RangeX_X'
ELSE 'Unknown'
END
FROM master.dbo.syslockinfo
GO
4
master.dbo.sysprocesses - System table with the process information across the SQL Server instance
SELECT *
FROM master.dbo.sysprocesses
GO


 

SQL Server 2005
In SQL Server 2005, these objects remain available but some are scheduled to be deprecated in SQL Server 2008 which means now is the time to make sure you transition your scripts prior to the SQL Server 2008 migration:
  • sp_lock - For backward compatibility only and expected to be deprecated in SQL Server 2008
    • Replacement (SQL Server 2005) = sys.dm_tran_locks
    • Expected Replacement (SQL Server 2008) = sys.syslock_information
  • sp_who and sp_who2 - Not expected to be deprecated in SQL Server 2008
  • master.dbo.syslockinfo - For backward compatibility only and expected to be deprecated in SQL Server 2008
    • Replacement (SQL Server 2005) = sys.dm_tran_locks
    • Expected Replacement (SQL Server 2008) = sys.syslock_information
  • master.dbo.sysprocesses - For backward compatibility only and expected to be deprecated in SQL Server 2008
    • Replacement (SQL Server 2005) = sys.dm_exec_connections, sys.dm_exec_sessions, sys.dm_exec_requests
      • Stay tuned for an upcoming tip on the mapping and opportunities with these three DMVs
With the sys.dm_tran_locks DMV in SQL Server 2005 functionally replacing sp_lock and master.dbo.syslockinfo a simple query can be issued to capture the pertinent locking related information. The resource related information (ResourceSubType, ResourceType, Request_Owner_Type, etc.) has all be provided as a descriptive name as opposed to having to write case statements to decipher the values. As such, this simplifies the overall querying as well as provides the opportunity to query supported objects and issue COUNT commands, determine specific lock types, etc.


SQL Server 2005 - master.sys.dm_tran_locks
-- Simple query to return all records and all columns
SELECT *
FROM master.sys.dm_tran_locks;
GO
-- Focused result set
SELECT resource_type, request_session_id, resource_database_id, resource_associated_entity_id, resource_subtype, resource_description, request_status, request_owner_type, request_mode
FROM sys.dm_tran_locks;
GO
-- Number of lock records per database
SELECT COUNT(*) AS 'NumberofLockRecords', DB_NAME(resource_database_id)
FROM master.sys.dm_tran_locks
GROUP BY resource_database_id;
GO
-- Query for specific lock types
SELECT resource_type, request_session_id, resource_database_id, resource_associated_entity_id, resource_subtype, resource_description, request_status, request_owner_type, request_mode
FROM sys.dm_tran_locks
WHERE resource_type IN ('PAGE', 'KEY', 'EXTENT', 'RID');
GO
SELECT tl.request_session_id, wt.blocking_session_id, DB_NAME(tl.resource_database_id) AS DatabaseName, tl.resource_type, tl.request_mode, tl.resource_associated_entity_id
FROM sys.dm_tran_locks as tl
INNER JOIN sys.dm_os_waiting_tasks as wt
ON tl.lock_owner_address = wt.resource_address;
GO

 
 
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