Re: ts_rank

Robert Haas wrote:
> Mark wrote:

>> Could somebody explain me on which methods is based ts_rank and
>> how it works? I would appreciate some articles, if exist.

> As far as I can tell, our documentation contains no useful
> information on this topic whatsoever. :-(

There's some potentially useful information here:

http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING

Although I don't know if it addresses Mark's question very well.
Personally, I wonder how relevant ts_rank will be after knn-giswt
is out....

-Kevin

On Thu, May 19, 2011 at 10:42 PM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> Robert Haas  wrote:
>> Mark  wrote:
>
>>> Could somebody explain me on which methods is based ts_rank and
>>> how it works?  I would appreciate some articles, if exist.
>
>> As far as I can tell, our documentation contains no useful
>> information on this topic whatsoever. :-(
>
> There's some potentially useful information here:
>
> http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING

Ah, yes. I didn't read that carefully enough. That is useful, but it
doesn't really explain how it works.

> Although I don't know if it addresses Mark's question very well.
> Personally, I wonder how relevant ts_rank will be after knn-giswt
> is out....

I don't see why it would be any less useful... though if someone could
find a way to KNN-ify such searches, I'm sure there would be a lot of
very happy users. Seems pretty difficult, though.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

>There's some potentially useful information here:
>http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING

Thanks for reply. I was reading the documentation of PostgreSQL, but there
it is not written the name of the used methods. Everywhere there is written,
that ts_rank use standard ranking function. But it is difficult to say which
is the standard function.
Somewhere I found that it is maybe based on Vector space model and it seems
to be truth, because in the code of tsrank.c is counted the frequency of
words, but I am not sure of that :-(

--
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Mark wrote:
> >There's some potentially useful information here:
> >http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING
>
> Thanks for reply. I was reading the documentation of PostgreSQL, but there
> it is not written the name of the used methods. Everywhere there is written,
> that ts_rank use standard ranking function. But it is difficult to say which
> is the standard function.
> Somewhere I found that it is maybe based on Vector space model and it seems
> to be truth, because in the code of tsrank.c is counted the frequency of
> words, but I am not sure of that :-(

Oleg, Teodor, can you give me a description of how ts_rank decided how
to rank items? Thanks.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +

Bruce Momjian wrote:
> Mark wrote:
> > >There's some potentially useful information here:
> > >http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING
> >
> > Thanks for reply. I was reading the documentation of PostgreSQL, but there
> > it is not written the name of the used methods. Everywhere there is written,
> > that ts_rank use standard ranking function. But it is difficult to say which
> > is the standard function.
> > Somewhere I found that it is maybe based on Vector space model and it seems
> > to be truth, because in the code of tsrank.c is counted the frequency of
> > words, but I am not sure of that :-(
>
> Oleg, Teodor, can you give me a description of how ts_rank decided how
> to rank items? Thanks.

Any news on this question?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +

I'm sorry, my plane to Nepal is waiting me :) I'll be back in the
midst of November. In short, ts_rank is based only on frequencies of lexems
and doesn't count distance between query lexems. Also, it supports only
primitive queries.

Oleg
On Wed, 12 Oct 2011, Bruce Momjian wrote:

> Bruce Momjian wrote:
>> Mark wrote:
>>>> There's some potentially useful information here:
>>>> http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING
>>>
>>> Thanks for reply. I was reading the documentation of PostgreSQL, but there
>>> it is not written the name of the used methods. Everywhere there is written,
>>> that ts_rank use standard ranking function. But it is difficult to say which
>>> is the standard function.
>>> Somewhere I found that it is maybe based on Vector space model and it seems
>>> to be truth, because in the code of tsrank.c is counted the frequency of
>>> words, but I am not sure of that :-(
>>
>> Oleg, Teodor, can you give me a description of how ts_rank decided how
>> to rank items? Thanks.
>
> Any news on this question?
>
>

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

Oleg Bartunov wrote:
> I'm sorry, my plane to Nepal is waiting me :) I'll be back in the
> midst of November. In short, ts_rank is based only on frequencies of lexems
> and doesn't count distance between query lexems. Also, it supports only
> primitive queries.

Thanks. Attached doc patch applied to head and 9.1.X.

---------------------------------------------------------------------------

>
> Oleg
> On Wed, 12 Oct 2011, Bruce Momjian wrote:
>
> > Bruce Momjian wrote:
> >> Mark wrote:
> >>>> There's some potentially useful information here:
> >>>> http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-RANKING
> >>>
> >>> Thanks for reply. I was reading the documentation of PostgreSQL, but there
> >>> it is not written the name of the used methods. Everywhere there is written,
> >>> that ts_rank use standard ranking function. But it is difficult to say which
> >>> is the standard function.
> >>> Somewhere I found that it is maybe based on Vector space model and it seems
> >>> to be truth, because in the code of tsrank.c is counted the frequency of
> >>> words, but I am not sure of that :-(
> >>
> >> Oleg, Teodor, can you give me a description of how ts_rank decided how
> >> to rank items? Thanks.
> >
> > Any news on this question?
> >
> >
>
> Regards,
> Oleg
> _____________________________________________________________
> Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
> Sternberg Astronomical Institute, Moscow University, Russia
> Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
> phone: +007(495)939-16-83, +007(495)939-23-83

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +