Re: max relations in a single database

FWIW, I built PG 7.2.1 sources here (on a RHL 7.2 box) using
    ./configure --enable-cassert --enable-debug
    set INDEX_MAX_KEYS to 64 in src/include/pg_config.h
    make all; make install
and ran the regression tests without seeing any problem.  This is
hardly conclusive since you may have used different configure options,
but it does tell me that there's not anything seriously wrong with
setting INDEX_MAX_KEYS = 64.

Have you tried running the regression tests on your installation?

            regards, tom lane