Обсуждение: pgsql: Tweak choose_bitmap_and() heuristics in the light of example

Log Message:
-----------
Tweak choose_bitmap_and() heuristics in the light of example provided in bug
#2075: consider an index redundant if any of its index conditions were already
used, rather than if all of them were.  Also, make the selectivity comparison
a bit fuzzy, so that very small differences in estimated selectivities don't
skew the results.

Modified Files:
--------------
    pgsql/src/backend/optimizer/path:
        indxpath.c (r1.194 -> r1.195)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/indxpath.c.diff?r1=1.194&r2=1.195)