Measuring Transactional Replication Latency Without Tracer Tokens

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Declare @Publisher sysname,
      @PublisherDB sysname;
 
-- Set Publisher server name
Set @Publisher = 'Publisher server name';
-- Set Publisher database name
Set @PublisherDB = 'Publisher database name'; 
 
-- Refresh replication monitor data
Exec sys.sp_replmonitorrefreshjob @iterations = 1;
 
With MaxXact (ServerName, PublisherDBID, XactSeqNo)
As (Select S.name, DA.publisher_database_id, max(H.xact_seqno)
      From dbo.MSdistribution_history H with(nolock)
      Inner Join dbo.MSdistribution_agents DA with(nolock)
            On DA.id = H.agent_id
      Inner Join master.sys.servers S with(nolock)
            On S.server_id = DA.subscriber_id
      Where DA.publisher_db = @PublisherDB
      Group By S.name, DA.publisher_database_id)
, OldestXact (ServerName, OldestEntryTime)
As (Select MX.ServerName, Min(entry_time)
      From dbo.msrepl_transactions T with(nolock)
      Inner Join MaxXact MX
            On MX.XactSeqNo < T.xact_seqno
            And MX.PublisherDBID = T.publisher_database_id
      Group By MX.ServerName)
Select [Replication Status] = Case MD.status
                  When 1 Then 'Started'
                  When 2 Then 'Succeeded'
                  When 3 Then 'In progress'
                  When 4 Then 'Idle'
                  When 5 Then 'Retrying'
                  When 6 Then 'Failed'
            End,
      Subscriber = SubString(MD.agent_name, 
                              Len(MD.publisher) + Len(MD.publisher_db) + Len(MD.publication) + 4, 
                              Charindex('-', MD.agent_name, 
                                    Len(MD.publisher) + Len(MD.publisher_db) + Len(MD.publication) + 5) - 
                                          (Len(MD.publisher) + Len(MD.publisher_db) + Len(MD.publication) + 4)), 
      [Subscriber DB] = A.subscriber_db, 
      [Publisher DB] = MD.publisher_db, 
      Publisher = MD.publisher,
      [Current Latency (sec)] = MD.cur_latency,
      [Current Latency (hh:mm:ss)] = Right('00' + Cast(MD.cur_latency/3600 As varchar), 2) +
                                                ':' + Right('00' + Cast((MD.cur_latency%3600)/60 As varchar), 2) +
                                                ':' + Right('00' + Cast(MD.cur_latency%60 As varchar), 2),
      [Latency Threshold (min)] = Cast(T.value As Int),
      [Agent Last Stopped (sec)] = DateDiff(hour, agentstoptime, getdate()) - 1, 
      [Agent Last Sync] = MD.last_distsync,
      [Last Entry TimeStamp] = OX.OldestEntryTime
From dbo.MSreplication_monitordata MD with(nolock)
Inner Join dbo.MSdistribution_agents A with(nolock)
      On A.id = MD.agent_id
Inner Join dbo.MSpublicationthresholds T with(nolock)
      On T.publication_id = MD.publication_id
      And T.metric_id = 2 -- Latency
Inner Join OldestXact OX
      On OX.ServerName = SubString(MD.agent_name, 
                              Len(MD.publisher) + Len(MD.publisher_db) + Len(MD.publication) + 4, 
                              Charindex('-', MD.agent_name, 
                                    Len(MD.publisher) + Len(MD.publisher_db) + Len(MD.publication) + 5) - 
                                          (Len(MD.publisher) + Len(MD.publisher_db) + Len(MD.publication) + 4))
Where MD.publisher = @Publisher
And MD.publisher_db = @PublisherDB
And MD.publication_type = 0 -- 0 = Transactional publication
And MD.agent_type = 3; -- 3 = distribution agent