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solrsimilarity

Solr Custom Similarity

i want to set my own custom similarity in my solr schema.xml but i have a few problems with understanding this feature. I want to completely deactivate solr scoring (tf,idf,coord and fieldNorm).

I dont know where to start. Things i know

  1. I have to write my own DefaultSimilarity implementation.
  2. Override the (tf,idf,coord and fieldNorm) - methods.
  3. Load the class in schem.xml

Where to store the class ? Are there any working examples in the web ? I cant find one!

THANKS

Solution

  • I figured it out on my own. I have stored my own implementation of DefaultSimilarity under /dist/ folder in solr. Then i add <lib dir="../../../dist/org/apache/lucene/search/similarities/" regex=".*\.jar"/> to my solrconfig.xml and everything works fine.

    package org.apache.lucene.search.similarities;
import org.apache.lucene.index.FieldInvertState;
import org.apache.lucene.search.similarities.DefaultSimilarity;

public class MyNewSimilarityClass extends DefaultSimilarity {

@Override
public float coord(int overlap, int maxOverlap) {
    return 1.0f;
}

@Override
public float idf(long docFreq, long numDocs) {
    return 1.0f;
}

@Override
public float lengthNorm(FieldInvertState arg0) {
    return 1.0f;
}

@Override
public float tf(float freq) {
    return 1.0f;
}

}

    Gist: https://gist.github.com/FabianKoestring/7846845