I see at least two possible approaches (each with their tradeoffs, neither great): 1. For each relevant foreign key, have an additional column without a constr

I see at least two possible approaches (each with their tradeoffs, neither great): 1. For each relevant foreign key, have an additional column without a constraint where the foreign key value can be copied to before deletion. (This requires that the original foreign key be nullable.) 2. Make soft deletion universal so that foreign keys can remain and any associated rows will still exist.