Typical rails/django-style migrations have the problem of being coupled to a particular app/language - so you'll need to work directly at the level of the datab

Typical rails/django-style migrations have the problem of being coupled to a particular app/language - so you'll need to work directly at the level of the database. You should add as much testing as possible - ideally have a central project that manages the database structure, and test each change carefully. Within each app, explicitly test that the app supports the intended new schema before moving to it. Use a schema diff tool to autogenerate migration scripts and check that they result in a perfectly matching schema - I wrote `migra` that works with postgres, but there are good equivalents for most databases.