The code equivalent of a "migration" is that you just write a new function that takes your new desired argument types, and then have the old function perform wh

The code equivalent of a "migration" is that you just write a new function that takes your new desired argument types, and then have the old function perform whatever type conversion is necessary and call the new. If writing such a function is not possible (because there is no automated way to convert from the old function call style to the new) then a database-style automated migration isn't going to be possible either.