$ script/generate migration CacheTextProcessing
class CacheTextProcessing < ActiveRecord::Migration
  def self.up
    rename_column :textilized_contents, :body,          :body_raw
    add_column    :textilized_contents, :body_rendered, :text

    # saving the record re-renders it
    TextilizedContent.find(:all).each {|tc| tc.save}
  end

  def self.down
    rename_column :textilized_contents, :body_raw, :body
    remove_column :textilized_contents, :body_rendered
  end
end