Prefix search, word completion, full text search

Hi !

I am  playing with the new full  text search in PostgreSQL  8.3. I would
like to search for prefixes to  allow to complete words. For example, if
I have  the lexemes 'foo', 'foobar' and  'bar', I would like  to get all
the words whose prefix is 'foo', i.e 'foo' and 'foobar'.

GIST or  GIN (I don't remember)  should allow to search  for prefix. How
can I query them?

Thanks.
--
BOFH excuse #348:
We're on Token Ring, and it looks like the token got loose.