> links=# select * from foo where a < 'Test0'::bpchar;
> a
> ---
> (0 rows)
> links=#
> Are you saying the second test should have returned true under C locale?
Yes. You are not really in C locale, or at least your postmaster isn't.
This looks like ISO sorting rules to me --- perhaps you are in en_US
locale.
> Is this a version dependant bug? Will downgrading to 6.x get me going?
No. Fix your locale. I'm afraid I don't have any more advice to offer
on that than I gave already ...
regards, tom lane