Rails: Is it bad to have an irreversible migration?

Question

When is it acceptable to raise an ActiveRecord::IrreversibleMigration exception in the self.down method of a migration? When should you take the effort to actually implemen

Answer 1

Feeling like you need an irreversible migration is probably a sign you've got bigger problems looming. Maybe some specifics would help?

As for your second question: I always take the 'effort' to write the reverse of migrations. Of course, I don't actually write the .down, TextMate inserts it automatically when creating the .up.