I've always done data migrations like that, by hand, with straight up SQL. It would seem to me that there'd be way too many combinations of changes to properly

I've always done data migrations like that, by hand, with straight up SQL. It would seem to me that there'd be way too many combinations of changes to properly implement in a generic way. Although, after reading your comment, I'd never taken 3rd party libraries into account. Adding/changing timezone support to a datetime field is a really good example of when that might be necessary. The groundwork has been laid with an API and supporting infrastructure for schema migrations though. It looks like it should be possible to implement data migrations by adding Operations to django.db.migrations.operations, and suitable sql and methods to each of the backends. You could then hand-craft the migration files. I'm assuming that the logic behind migrations wouldn't verify the database/model structure before running such a data migration which is probably flat out wrong though.