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.
On Wed, Mar 7, 2012 at 18:59, Andrey Chursin <andll(at)danasoft(dot)ws> wrote:
> Is there any way to sort by ranking, avoiding seq scan?
> The only way i see now is to use pg_trgm instead of ts_rank, but we
> did not check yet how applicable is it for our purposes.
>