Julien Rouhaud <julien.rouh...@dalibo.com> writes: > I wonder if in remove_useless_groupby_columns(), in the foreach loop you > could change the
> + if (bms_subset_compare(pkattnos, relattnos) == BMS_SUBSET1) > + { > by something like > + if (bms_num_members(relattnos) <= bms_num_members(pkattnos)) > + continue; > + > + if (bms_is_subset(pkattnos, relattnos)) > + { > which may be cheaper. FWIW, I really doubt that would be cheaper. The various flavors of subset comparison are word-at-a-time bitmasking operations, but bms_num_members has to grovel over individual bits; it's certain to be more expensive than a subset test. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers