# File lib/big_record/model.rb, line 837
      def columns_hash
        unless @all_columns_hash
          # add default hbase columns
          @all_columns_hash =
            if self == base_class
              if @columns_hash
                default_columns.merge(@columns_hash)
              else
                @columns_hash = default_columns
              end
            else
              if @columns_hash
                superclass.columns_hash.merge(@columns_hash)
              else
                superclass.columns_hash
              end
            end
        end
        @all_columns_hash
      end