"PostgreSQL Bugs List" <pgsql-bugs(at)postgresql(dot)org> writes:
> i passed the same query to a same database but on a linux machine with
> postgres 7.4.2 it returned me around 5 rows which is not correct .
I'd guess that you are using the wrong character set encoding in the
Linux database. You did not say what encoding you think these strings
are in, but it seems possible that strings containing characters that
are illegal in the current encoding might be considered equal.
regards, tom lane