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From "Doron Cohen" <cdor...@gmail.com>
Subject Re: Re[2]: lucene scoring
Date Fri, 08 Aug 2008 19:44:28 GMT
Following suggestion is weaker than the requested functionality, but
maybe you'll find the concept useful to ignore so called "garbage" results.

Assume that the query is a simple OR query made of a few words.
By examining the frequencies of these words in the index
(their DFs) devise a synthetic document which is the worst
document you will be willing to accept as a useful result.
Alternatively ignore DFs, but create a few documents like this -
each perhaps containing one or few of the query words (and likely
many other words). Now virtually add the synthetic document(s)
to the index. Can be done by creating a small in memory index,
and creating a multiIndexReader on top of the real index and
the dummy one. Now execute the query, with a filter that
accepts only the synthetic documents. The score of the worst
acceptable document(s) can be used as a threshold when
running the query on the original index.

It is inefficient - should be done for each query, and would be hard
to implement for general queries, and I never tried it...

Doron

2008/8/8 Александр Аристов <cloun203@mail.ru>

> Query independent means that the threshold should have the same relevance
> for all queries and discard found docs below it. Current scoring
> implementation doesn't give guaranties that, say two documents found in two
> queries and which got the same score 0.5 are of the same quality.
>
> I don't want discarding docs from being indexed, no. But I want to be sure
> that two docs with the same score in two different queries have the same
> quality (they contain the same set of found terms, lenght etc.)
>
> Alexander
>
> -----Original Message-----
> From: Andrzej Bialecki <ab@getopt.org>
> To: java-dev@lucene.apache.org
> Date: Thu, 07 Aug 2008 22:44:46 +0200
> Subject: Re: lucene scoring
>
>
> Александр Аристов wrote:
> > I want implement searching with ability to set so-called a confidence
> > level below which I would treat documents as garbage. I cannot defile
> > the level per query as the level should be relevant for all
> > documents.
>
> Hmm .. I'm not sure if I understand it properly - if the level is
> query-independent, then it's a constant factor, which you can put in a
> field during the index creation - and then you could use a Filter or
> FunctionQuery to exclude documents with this factor below the threshold.
>
> --
> Best regards,
> Andrzej Bialecki     <><
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