Needed by db-to-sqlite. It currently works by collecting all of the foreign key relationships it can find and then applying them at the end of the process.

The problem is, the add_foreign_key() method looks like this:

That means it's doing a full VACUUM for every single relationship it sets up - and if you have hundreds of foreign key relationships in your database this can take hours.

I think the right solution is to have a .add_foreign_keys(list_of_args) method which does the bulk operation and then a single VACUUM. .add_foreign_key(...) can then call the bulk action with a single list item.