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From Otis Gospodnetic <otis_gospodne...@yahoo.com>
Subject Scoring in MatchAllDocsQuery & ConstantScoreQuery
Date Sat, 25 Nov 2006 06:59:41 GMT
Hi,

Poking around Query/Weight/Scorer classes I finally started understanding how some portions
of the scoring works (imagine a lot of lightbulbs now).  In one of my Lucene use-cases I really
just use it to pull N documents from an index, and don't care for score (I sort by time).
 That lead me to look at MatchAllDocsQuery and ConstantScoreQuery.  I see they don't do anything
with IDF nor anything fancy with Similarity, and instead both queries return a score equal
to the query boost.  Still, why do they even bother with the multiplications in sumOfSquaredWeights()
and normalize(float) methods?

    public float sumOfSquaredWeights() {
      queryWeight = getBoost();
      return queryWeight * queryWeight;
    }

    public void normalize(float queryNorm) {
      this.queryNorm = queryNorm;
      queryWeight *= this.queryNorm;
    }

Shouldn't that queryWeight = getBoost() be enough to get the query boost and use it as a score?
Obviously, not all lightbulbs are on yet...

Thanks,
Otis



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