snippet.rb

  # Warning: Loses any scope it may have been called on!
  def send_all_in_batches(batch_size, method, *args)
    transaction do
      start_id = first(:order => 'id ASC').id
      end_id = first(:order => 'id DESC').id
      current_id = start_id
      while current_id <= end_id
        send_later :send_to_batch, current_id, current_id + batch_size, method, *args)
        current_id += batch_size
      end
    end
  end
  
  # Warning: Loses any scope it may have been called on!
  def send_to_batch(start_id, end_id, method, *args)
    all(:conditions => ['id >= ? AND id < ?', start_id, end_id]).each do |object|
      object.send(method, *args)
    end
  end