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From scott w <scottbl...@gmail.com>
Subject Re: Question about how to speed up custom scoring
Date Fri, 09 Oct 2009 21:18:03 GMT
(Apologies if this message gets sent more than once. I received an error
sending it the first two times so sent directly to Jake but reposting to
group.)
Hi Jake --

Thanks for the feedback.

What I am trying to implement is a way to custom score documents using a
scoring function that takes as input a map of fields (which may or may not
be in any given document) and weights for those fields supplied at query
time, and outputs an aggregate score that is based on taking the numeric
field weights that are already stored and indexed and then readjusting those
weights based on the map.

Another thing I would like to do is the same thing but for fields that do
not have weights associated with them in the index and so the query time
supplied weights essentially get used directly instead of adjusting the
already indexed weights.

You can think of this is as implementing a form of personalization where you
have a default set of weights and you want to adjust them on the fly
although our use case is a little different.

thanks,
Scott

On Fri, Oct 9, 2009 at 10:40 AM, Jake Mannix <jake.mannix@gmail.com> wrote:

> Scott,
>
>  To reiterate what Erick and Andrzej's said: calling
> IndexReader.document(docId)
> in your inner scoring loop is the source of your performance problem -
> iterating
> over all these stored fields is what is killing you.
>
>  To do this a better way, can you try to explain exactly what this Scorer
> is
> supposed to be doing?  You're extending CustomScoreQuery and which
> is usually used with ValueSourceQuery, but you don't use that part, and
> ignore the valSrcScore in your computation.
>
>  Where are the parts of your score coming from?  The termWeight map
> is used how exactly?
>
>  -jake
>
> On Fri, Oct 9, 2009 at 10:30 AM, scott w <scottblanc@gmail.com> wrote:
>
> > Thanks for the suggestions Erick. I am using Lucene 2.3. Terms are stored
> > and given Andrzej's comments in the follow up email sounds like it's not
> > the
> > stored field issue. I'll keep investigating...
> >
> > thanks,
> > Scott
> >
> > On Thu, Oct 8, 2009 at 8:06 AM, Erick Erickson <erickerickson@gmail.com
> > >wrote:
> >
> > > I suspect your problem here is the line:
> > > document = indexReader.document( doc );
> > >
> > > See the caution in the docs
> > >
> > > You could try using lazy loading (so you don't load all
> > > the terms of the document, just those you're interested
> > > in). And I *think* (but it's been a while) that if the terms
> > > you load are indexed that'll help. But this is mostly
> > > a guess.
> > >
> > > What version of Lucene are you using???
> > >
> > > Good luck!
> > > Erick
> > >
> > > On Thu, Oct 8, 2009 at 10:56 AM, scott w <scottblanc@gmail.com> wrote:
> > >
> > > > Oops, forgot to include the class I mentioned. Here it is:
> > > >
> > > > public class QueryTermBoostingQuery extends CustomScoreQuery {
> > > >  private Map<String, Float> queryTermWeights;
> > > >  private float bias;
> > > >  private IndexReader indexReader;
> > > >
> > > >  public QueryTermBoostingQuery( Query q, Map<String, Float>
> > termWeights,
> > > > IndexReader indexReader, float bias) {
> > > >    super( q );
> > > >    this.indexReader = indexReader;
> > > >    if (bias < 0 || bias > 1) {
> > > >      throw new IllegalArgumentException( "Bias must be between 0 and
> 1"
> > > );
> > > >    }
> > > >    this.bias = bias;
> > > >    queryTermWeights = termWeights;
> > > >  }
> > > >
> > > >  @Override
> > > >  public float customScore( int doc, float subQueryScore, float
> > > valSrcScore
> > > > ) {
> > > >    Document document;
> > > >    try {
> > > >      document = indexReader.document( doc );
> > > >    } catch (IOException e) {
> > > >      throw new SearchException( e );
> > > >    }
> > > >    float termWeightedScore = 0;
> > > >
> > > >    for (String field : queryTermWeights.keySet()) {
> > > >      String docFieldValue = document.get( field );
> > > >      if (docFieldValue != null) {
> > > >        Float weight = queryTermWeights.get( field );
> > > >        if (weight != null) {
> > > >          termWeightedScore += weight * Float.parseFloat(
> docFieldValue
> > );
> > > >        }
> > > >      }
> > > >    }
> > > >    return bias * subQueryScore + (1 - bias) * termWeightedScore;
> > > >   }
> > > > }
> > > >
> > > > On Thu, Oct 8, 2009 at 7:54 AM, scott w <scottblanc@gmail.com>
> wrote:
> > > >
> > > > > I am trying to come up with a performant query that will allow me
> to
> > > use
> > > > a
> > > > > custom score where the custom score is a sum-product over a set of
> > > query
> > > > > time weights where each weight gets applied only if the query time
> > term
> > > > > exists in the document . So for example if I have a doc with three
> > > > fields:
> > > > > company=Microsoft, city=Redmond, and size=large, I may want to
> score
> > > that
> > > > > document according to the following function: city==Microsoft ? .3
> :
> > 0
> > > *
> > > > > size ==large ? 0.5 : 0 to get a score of 0.8. Attached is a
> subclass
> > I
> > > > have
> > > > > tested that implements this with one extra component which is that
> it
> > > > allow
> > > > > the relevance score to be combined in.
> > > > >
> > > > > The problem is this custom score is not performant at all. For
> > example,
> > > > on
> > > > > a small index of 5 million documents with 10 weights passed in it
> > does
> > > > 0.01
> > > > > req/sec.
> > > > >
> > > > > Are there ways to make to compute the same custom score but in a
> much
> > > > more
> > > > > performant way?
> > > > >
> > > > > thanks,
> > > > > Scott
> > > > >
> > > >
> > >
> >
>

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