Re: First implementation of GIN for pg_trgm

On Thu, 22 Feb 2007, Guillaume Smet wrote:

> On 2/22/07, Teodor Sigaev <teodor@sigaev.ru> wrote:
>> How long is average length of strings in table?
>
> test=# SELECT MIN(length(word)), MAX(length(word)), AVG(length(word))
> FROM lieu_mots_gin;
> min | max |        avg
> -----+-----+--------------------
>  1 |  38 | 7.4615463141373282
> (1 row)
>
> I don't see how to have a more precise similarity without having the
> number of entries registered by the indexed value somewhere.
>
> I think it can be interesting for other flavours of GIN usage. Is
> there a way to add the number of entries of the considered indexed
> item to the consistent prototype without adding too much overhead and
> complexity?

You're right, it would be nice.
This is what we need for faster ranking in tsearch2, since currently we should
consult heap to get positional information, which slowdowns search.
We didn't investigate the possibility to keep additional information with
index, but keep in mind, that everything should works without index.

     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