interesting question.

we roll forward and thus far never ran into the situation that that wasn't possible in a reasonable amount of time.

nevertheless i've wondered more than once what would happen if we run into such a situation and there's a substantial database migration in the process (i.e. with table drops).

curious to learn what the different strategies are on that point: do you put your table contents in the down migration, do you revert to the last backup, etc.