How to migrate database down on rollback?

[airblade]

I am setting up git-deploy to use with a Rails app and I'm looking at rollbacks.

The rollback code resets the working tree to before the last push, then executes either deploy/rollback or deploy/after_push.

If I'm rolling back I want to migrate the database down to where it was, probably using rake db:migrate VERSION=x where the script figures out what x is.

However I can't do this in deploy/rollback because the migration files have already been removed by the git reset --hard.

I can't even do this by hand after rolling back, for the same reason.

Any help would be much appreciated!

[airblade]

I see capistrano-rails doesn't rollback the database. Instead they advise writing backward-compatible migrations which one then cleans up later after a successful deployment.