尋找持有最多鎖定的物件

資料庫管理員經常需要識別阻礙資料庫效能的鎖定來源。

例如，您正在監視實際伺服器，以找出任何可能的瓶頸。 您懷疑可能有高度爭用的資源，而且想要了解這些物件所持有的鎖定數量。 一旦識別出最常鎖定的物件之後，就可以採取步驟來最佳化爭用物件的存取。

若要這樣做，請在 SQL Server Management Studio 中使用查詢編輯器。

尋找持有最多鎖定的物件

• 在查詢編輯器中，發出下列陳述式。

  -- Find objects in a particular database that have the most
  -- lock acquired. This sample uses AdventureWorksDW2012.
  -- Create the session and add an event and target.
  -- 
  IF EXISTS(SELECT * FROM sys.server_event_sessions WHERE name='LockCounts')
  DROP EVENT session LockCounts ON SERVER
  GO
  DECLARE @dbid int
  
  SELECT @dbid = db_id('AdventureWorksDW2012')
  
  DECLARE @sql nvarchar(1024)
  SET @sql = '
  CREATE event session LockCounts ON SERVER
  ADD EVENT sqlserver.lock_acquired (WHERE database_id =' + CAST(@dbid AS nvarchar) +')
  ADD TARGET package0.histogram( 
  SET filtering_event_name=''sqlserver.lock_acquired'', source_type=0, source=''resource_0'')'
  
  EXEC (@sql)
  GO
  ALTER EVENT session LockCounts ON SERVER 
  STATE=start
  GO
  -- 
  -- Create a simple workload that takes locks.
  -- 
  USE AdventureWorksDW2012
  GO
  SELECT TOP 1 * FROM dbo.vAssocSeqLineItems
  GO
  -- The histogram target output is available from the 
  -- sys.dm_xe_session_targets dynamic management view in
  -- XML format.
  -- The following query joins the bucketizing target output with
  -- sys.objects to obtain the object names.
  --
  SELECT name, object_id, lock_count FROM 
  (SELECT objstats.value('.','bigint') AS lobject_id, 
  objstats.value('@count', 'bigint') AS lock_count
  FROM (
  SELECT CAST(xest.target_data AS XML)
  LockData
  FROM sys.dm_xe_session_targets xest
  JOIN sys.dm_xe_sessions xes ON xes.address = xest.event_session_address
  JOIN sys.server_event_sessions ses ON xes.name = ses.name
  WHERE xest.target_name = 'histogram' AND xes.name = 'LockCounts'
  ) Locks
  CROSS APPLY LockData.nodes('//HistogramTarget/Slot') AS T(objstats)
   ) LockedObjects 
  INNER JOIN sys.objects o
  ON LockedObjects.lobject_id = o.object_id
  WHERE o.type != 'S' AND o.type = 'U'
  ORDER BY lock_count desc
  GO
  -- 
  -- Stop the event session.
  -- 
  ALTER EVENT SESSION LockCounts ON SERVER
  state=stop
  GO
  

當此程序中的陳述式完成之後，查詢編輯器的 [結果] 索引標籤會顯示以下資料行：

• name

• object_id

• lock_count

請參閱

參考

CREATE EVENT SESSION (Transact-SQL)

ALTER EVENT SESSION (Transact-SQL)

sys.dm_xe_session_targets (Transact-SQL)

sys.dm_xe_sessions (Transact-SQL)

sys.server_event_sessions (Transact-SQL)