如何查找具有最多锁定的对象

数据库管理员通常需要识别影响数据库性能的锁定来源。

例如,可以监视生产服务器是否存在任何可能的瓶颈。您怀疑可能存在高度争用的资源,并希望了解这些对象占用多少锁定。一旦识别锁定频率最高的对象,便可采取一些措施来优化对争用对象的访问。

为此,请使用 SQL Server Management Studio 中的查询编辑器。

查找占用最多锁定的对象

  • 在查询编辑器中发出以下语句:

    -- Find objects in a particular database that have the most
    -- lock acquired. This sample uses AdventureWorks_DW.
    -- 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('AdventureWorksDW')
    
    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.synchronous_bucketizer ( 
    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 AdventureWorksDW
    GO
    SELECT TOP 1 * FROM dbo.vAssocSeqLineItems
    GO
    -- Bucketizing 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 = 'synchronous_bucketizer' AND xes.name = 'LockCounts'
    ) Locks
    CROSS APPLY LockData.nodes('//BucketizerTarget/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
    

此过程中的语句完成后,查询编辑器的**“结果”**选项卡将显示以下列:

  • name

  • object_id

  • lock_count