CODEWITHSUNDEEP
solr
Tsung Lin Tsai
Tsung Lin Tsai

Reputation: 661

disable lengthNorm (length normalization)

I would like to disable lengthNorm in Solr. Some people suggest using omitNorms=true. but I can't use it because I also want to do index time boost. "omitNorms=true" seems to disable index time boost. another approach I found online is to override lengthNorm method in DefaultSimilarty. but looks like this method is no longer used in Solr 4.0. Is there another other way to do so?

public float lengthNorm(String fieldName, int numTerms) {
    return numTerms > 0 ? 1.0f : 0.0f;
}

Upvotes: 0

Views: 749

Answers (1)

Jayendra
Jayendra

Reputation: 52799

You can check the source of DefaultSimilarity for 4.0

@Override
public void computeNorm(FieldInvertState state, Norm norm) {
    final int numTerms;
    if (discountOverlaps)
        numTerms = state.getLength() - state.getNumOverlap();
    else
        numTerms = state.getLength();
    norm.setByte(encodeNormValue(state.getBoost() * ((float) (1.0 / Math.sqrt(numTerms)))));
}

You can create a Custom class with numTerms equal to 1 or remove the calculation ((float) (1.0 / Math.sqrt(numTerms))) to eliminate lengthNorm effect.

Upvotes: 1

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