"Octavio Alvarez" <alvarezp@octavio.ods.org> writes:
> I don't know if detection of which keys are equal (in this case
> octav=OCTAV=OCTAV) should be made by PostgreSQL or libc. I also don't know
> if I am wrong assuming octav=OCTAV. For alphabetic sorting, it should be
> case insensitive.
I believe that the usual locale definitions set things up so that
strings of different case are not "equal", but case differences are
the last tiebreaker when sorting. So "octav" sorts before "OCTAV"
but after everything else that's less than "OCTAV".
I haven't studied your results to see if they are consistent with
that viewpoint, but I'm really not ready to believe that Postgres
is sorting in a way that's not what the active locale says to do.
We have not heard such a report before. (We have, on the other
hand, heard from lots of people who were surprised at the properties
of their default locale ...)
regards, tom lane