Обсуждение: pgsql: Department of second thoughts: fix newly-added code in planner.c

Log Message:
-----------
Department of second thoughts: fix newly-added code in planner.c to make real
sure that DISTINCT ON does what it's supposed to, ie, sort by the full ORDER
BY list before unique-ifying.  The error seems masked in simple cases by the
fact that query_planner won't return query pathkeys that only partially match
the requested sort order, but I wouldn't want to bet that it couldn't be
exposed in some way or other.

Modified Files:
--------------
    pgsql/src/backend/optimizer/plan:
        planner.c (r1.238 -> r1.239)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planner.c?r1=1.238&r2=1.239)