gistfile1.rb

class BuildPropertyAssociationsOnExports < ActiveRecord::Migration
  ...
  
  class Property < ActiveRecord::Base
    attr_accessible :hierarchical
  end
  
  ...
  
  def up
    ActiveRecord::Base.connection.schema_cache.clear!
    Property.find_each do |property|
      if property.hierarchical?
        # Do something interesting 
      else
        # Do something less interesting
      end  
    end 
  end
  
  def down
    # undo some interesting things
  end
  
end