There is an auto_migrations plugin that people nowadays start using more and more often. This plugin allows to maintain only one file with database schema definitions and it changes DB structure to match that definition automagically.
Giles Bowkett blogged about it recently and about problems with regular migrations. But wait a minute, I've seen (and experienced) only one type of situations when you can't migrate from zero up to latest migration: it's situation when your model has changed through version and e.g. some method vital for that migration was removed or some new validation was added and you try to create objects in migration that have that field set to an invalid value.
How can changing DB structure make migrations invalid ?
And having that in mind, how that auto_migrations thing can help ? Also, how will you actually migrate your data with auto_migrations ?
PS btw, the way to fix broken migrations in situation described above is to use schema dump that rails creates anyways in db/ directory: when you create from scratch, there could be no data to migrate, so you could just create the DB structure. But if there are migrations to e.g. create an admin user, then you could need to run actual migrations. And the only way I see (when they fail half way) is to use version control system to update to each revision where new migration was added (so that source code match the migration), do the migration, then update to next version where new migration was introduced, do the migration and so forth. Probably, this could be automated. Assuming it is needed only when new member joins the development team, it is a rear operation so the performance is not critical.