A method of satisfying a database query includes evaluating certain joins on a per-segment basis. Invention is particularly aimed at generating novel polynucleotides that differ in some advantageous respect compared to a reference sequence. As the heat-absorbing area has a heat capacity larger than that in the other portions, the combustion heat is absorbed and dispersed even if the rapid chain reaction of PM combustion occurs, whereby it is possible to suppress the temperature rise of the downstream portion of the particulate filter liable to be high in temperature.