# File lib/thinking_sphinx/source/internal_properties.rb, line 4
      def add_internal_attributes_and_facets
        add_internal_attribute :sphinx_internal_id, nil,
          @model.primary_key_for_sphinx.to_sym
        add_internal_attribute :class_crc,          :integer, crc_column, true
        add_internal_attribute :sphinx_deleted,     :integer, "0"

        add_internal_facet :class_crc
      end