"no activity on the backup server" to me means "no backup jobs are running at this time from SQL", correct?  Are you 100% confident that your work will fit in...

Another thought - Visual Studio is 32-bit so the debugger is 32-bit.  SSIS is going to be 64 bit.  Just thinking of other things that may affect performance...

What happens to...

Is it the same account on the old system (NT Service\SQLSERVERAGENT) or do you have an actual account for it?

The proxy account will likely be your only option on the...

As a thought - can you log into the server as the SSIS Service account?  I am thinking about taking the opposite approach as Jeffery Williams (creating a proxy) and...

Another thought - do you NEED columnC in your FinalTable_bedeleted?  Probably speed things up a little bit by only pulling the ID's out of FinalTable, no?

Just thinking that 600 million...

I am pretty sure that SQL Prompt (at the moment) cannot colorize the tab based on the SQL login (Windows or SQL).  That is, if you log in as "sa"...

My opinion, no publicly facing messaging system should allow anyone except an account owner to post on their behalf.  That is a HUGE privacy concern and could be career ending...

First, having the data in a consumable format is something that will get you a LOT more replies.  The way you have it now, we have to do the leg-work...

My understanding of clustered columnstore indexes is that they are not ordered (except in Azure).  So, my opinion, your non-clustered indexes (the UNIQUE and the NONCLUSTERED are both NONCLUSTERED) may...

As far as I know, you can't change the color of SSMS based on who you connect as, but you can change the status bar color:

https://www.sqlshack.com/how-to-set-custom-colors-in-the-ssms-status-bar/

And, with a quick test...

Oh gotcha... Yep, that makes sense then.  You are more curious at the moment which queries may break by changing the index, not which indexes are in use and which...

Just putting my 2 cents in here but putting 300 GB of data on a 4 TB disk sounds like overkill.  If possible, I'd put it on a SAN and...

I don't see anything obvious (although I am not an XML guru by any means).

Have you thought about looking at the indexes and the data SQL stores on them rather...

Since on dev it uses all 56 GB of memory, you would need more than 56 free on live.  How much exactly, I am not sure.  But you can get...

Just to confirm this, you have 1 billion rows in around 5 or 6 tables that are changing frequently where the column needs to be updated?

There are always tricks you...