[alisonatwork]

It would be interesting to hear more about your experience with systems where deletion has been deemed "literally impossible".

Every database I have come across in my career has a delete function. Often it is slow. In many places I worked, deleting or expiring data cost almost as much as or sometimes more than inserting it... but we still expired the data because that's a fundamental requirement of the system. So everything costs 2x, so what? The interesting thing is how to make it cost less than 2x.