compute_column_widths

# File activerecord/lib/active_record/connection_adapters/mysql/explain_pretty_printer.rb, line 40
          def compute_column_widths(result)
            [].tap do |widths|
              result.columns.each_with_index do |column, i|
                cells_in_column = [column] + result.rows.map { |r| r[i].nil? ? "NULL" : r[i].to_s }
                widths << cells_in_column.map(&:length).max
              end
            end
          end