Re: tsearch2 questions

On Wed, 4 Jul 2007, Joshua N Pritikin wrote:

> 1. What is the advantage of the tsearch2() trigger? Why can't I write my
> own trigger which does approximately:

no advantage, it's just an example.


>
>  UPDATE manuscript set manuscript_vector =
>    setweight(to_tsvector(manuscript_genre), 'A') ||
>    setweight(to_tsvector(manuscript_title), 'B') ||
>    to_tsvector(manuscript_abstract);
>
> 2. Is there a way to know in advance the maximum return value of the
> rank function? I have lots of other information to include in the
> goodness-of-match score besides the fulltext match rank so I would
> prefer a tsearch2 rank score between 0 and 1. Do I need to write my own
> rank function?

what's about simple normalization formulae, like rank/(rank+1) ?


     Regards,
         Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83