# File lib/innodb/page/index.rb, line 333
  def record_header_compact_additional(header, cursor)
    case header[:type]
    when :conventional, :node_pointer
      # The variable-length part of the record header contains a
      # bit vector indicating NULL fields and the length of each
      # non-NULL variable-length field.
      if record_format
        header[:nulls] = cursor.name("nulls") {
          record_header_compact_null_bitmap(cursor)
        }
        header[:lengths], header[:externs] =
          cursor.name("lengths_and_externs") {
            record_header_compact_variable_lengths_and_externs(cursor,
              header[:nulls])
          }
      end
    end
  end