Re: TSearch and rankings

On Mon, 9 Feb 2004, Bas Scheffers wrote:

> Teodor Sigaev said:
> > (foo&bar)|(foo&bar&doh)
> > I think, it's what you want.
> That simple huh? Can become a bit complicated, doing an OR for all the
> different combinations, but a quick test I just did did show a higher
> ranking for the documents that matched the larger query. And quite usable
> in my application.
>
> Do big queries have a significant inpact on search performance? (this is
> something that is important!)

Sure :( In degenerated case you end with query like (word1|word2|word3|..|wordN)
and it's equivalent running N searches with single word query, which isn't
effective. Intrinsically, tsearch2 is much faster for long AND queries,
which is opposite to standard search engines based on inverted indexes.

>
> Thanks,
> Bas.
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo(at)postgresql(dot)org)
>

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83