tsql - Alternatives To Increase Performance? Using Outer Apply w/ Top1 and Order -

After

Thanks to my last question, I make a pile for my project to progress and even Learned a lot. I was hoping that I can get some help on this issue on which I am currently facing with performance hits. Actually we are working with a database called "AlertHistory" that is a table, and this table is not indexed (I know, ...). My goal here is to get the latest entry in the Alert History table that is related to current alertness. My thought here is to use an option to select AllAlerts.AlertID as

  AlertID, but this has gone from execution time ~ 20 seconds to ~ 3minutes).  as taken performance hit on a large scale on your production servers, as Queues.QueueID Kyuiaidi, Queues.QueueName as Kyuinam, ConnectorID as AllAlerts.ConnectorID, AllAlerts.DeviceID DeviceID, AllAlerts as .SituationMessage summary, as AllAlerts.AlertDetail detail, acknowledged as AllAlertskAcknowledged, "accepted" = case when AllAlerts .Acknowledged = '1' then History.CreatedBy when AllAlerts.Acknowledged = '0 'Then' 'End, AssignedTo, CreatedTime as AllAlerts.ReportedTime, ClearedTime as AllAlerts.ClearedTime [ISG_SOI] [Dbo]. [As AllAlerts.AssignedTo AllAlerts Internal Format Alert] [ISG_SOI] join. [Dbo]. [AlertQueueAssignments] On quality assurance as QA [AlertID] = AllAlerts [AlertID] Join Inner [ISG_SOI] [Dbo]. [AlertQueues] as queue on the queue. [QueueID] = qa [QueueID] external force ([ISG_SOI] select the top 1 History.CreatedBy from. [Dbo]. [AlertHistory] history as the History.ColumnName = '73, 549 'and History.AlertID = AllAlerts. Order by AlertID History.CreatedTime DESC ) As the history where Queues.QueueName = 'OCC'  

just apply to explain, columnName is a static column that I need to source. This database uses an integer identifier 73549. Of course I can use a 'declared' and declare a variable, but do not support our implementation software (BOXI).

  join the inner (select History.AlertID, Max (History.CreatedBy) [ the ISG_SOI] as CreatedBy. [dbo]. [AlertHistory] as the history of the group History.AlertID as history History.ColumnName = '73, 549 'History.AlertID = AllAlerts.AlertID)  < / pre> 
 and you can see joining a hash 
 signal or by merger should force be used only once to evaluate [Advanced Cverian tuning concepts] [1] 
 
 The next step is that Use Ri will make #temp. 
 Announce PK on AlertID as a query Optimizer can use that information.