# File lib/innodb/data_dictionary.rb, line 270
  def data_dictionary_index(table_name, index_name)
    unless table_entry = data_dictionary_indexes[table_name]
      raise "Unknown data dictionary table #{table_name}"
    end

    unless index_root_page = table_entry[index_name]
      raise "Unknown data dictionary index #{table_name}.#{index_name}"
    end

    # If we have a record describer for this index, load it.
    record_describer = data_dictionary_index_describer(table_name, index_name)

    system_space.index(index_root_page, record_describer)
  end