BTW, I have done quick-and-dirty tests of indexes with up to 16 keys
and SQL functions with up to 16 arguments, and both seem to work.
Did not try plpgsql or pltcl functions --- perhaps someone who's
handier than I am with those languages can check them.
I also committed a patch to ensure that index declarations with
more than INDEX_MAX_KEYS will be rejected; this oversight was
noted by Hiroshi a while ago.
regards, tom lane