If you add a column in a rails migration, rails will NOT correctly save to column in the same migration. You can access it and assign to it, but it will not be saved to the database ever.)

For example if you have something like:

class UpdateSubscriptions < ActiveRecord::Migration
  def up
    add_column :subscriptions, :user_id, :integer
    Subscription.all.each do |s|
      s.user = User.find_by_subscription_key( s.key )
      s.save
  end
end

Rails happily ignores your change and silently only updates the "updated_at" column (if you have timestamp columns).

So split this into 2 migrations! Or perhaps some amount of "reload!" type action might work as well..