[LUCENE-7395] Query Norm and coordination factor not calculated when PerFieldSimilarityWrapper is used

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.3.1, 5.4.1
• Fix Version/s: 6.2
• Lucene Fields: New
• Assignee: Uwe Schindler
• Reporter: Sascha Markus
• Created: 26/Feb/16 08:01
• Updated: 28/Aug/22 15:01
• Resolved: 27/Jul/16 08:08

Description

If any kind of similarity is defined and therefore the SchemaSimilarityFactory is defined as global similarity the queryNorm is always 1.0

The PerFieldSimilarityWrapper delegates some of the methods to the desired Similarity but misses to delegate public float queryNorm(float valueForNormalization)
Instead the IndexReader calls this method on the base class Similarity.

The result is that all scores are much higher.

I created a custom similarity which extends ClassicSimilarity.
To have the calculation fixed I did a local "hotfix" which always uses the default similarity. Also wrong for some cases but fine in my scenario.

@Override
public float queryNorm(float valueForNormalization)

{ return get("").queryNorm(valueForNormalization); // use default similarity to calculate }

Issue Links

• is duplicated by: SOLR-9315 SchemaSimilarityFactory should delegate queryNorm and coord to the default similarity