Strange behavior on to_tsquery()

Hello PG hackers,

I created a *custom dictionary* (based on dict_int) and a search
configuration and a strange behavior happens on *PostgreSQL 8.4.9*.

When I invoke the following instruction several times,*
to_tsquery()*returns distinct results:

catalog=> SELECT to_tsquery('custom', 'pi');
to_tsquery
------------
'pi':*
(1 registro)

catalog=> SELECT to_tsquery('custom', 'pi');
to_tsquery
------------
'pi'
(1 registro)

Therefore, when I use *@@ operator* over a *tsvector* column in my table
the result set is not always the same.

1) Do you have any clue on what could be happening and how to solve this
issue, please?

2) Sometimes the value returned by *to_tsquery()* has a ":*" suffix. What
does that mean?

Thanks in advance.

Best Regards,

--
Rodrigo Hjort
www.hjort.co