There is some good news coming from Oleg Bartunov and Alexander Korotkov
about improving ranking speed:
http://wiki.postgresql.org/images/2/25/Full-text_search_in_PostgreSQL_in_milliseconds-extended-version.pdf
It's worth reading their slides to gain a better understanding of
PostgreSQL fulltext internals.
On Wed, Mar 7, 2012 at 8:05 PM, Nicolas Grilly <nicolas(at)gardentechno(dot)com>wrote:
> In a previous discussion thread, Oleg suggested that ts_rank is unable to
> use GIN indices:
> http://archives.postgresql.org/pgsql-general/2011-07/msg00351.php
>
> This is the only information I have about this.
>