[LUCENE-8216] Better cross-field scoring

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 8.0
• Lucene Fields: New
• Assignee: Jim Ferenczi
• Reporter: Adrien Grand
• Created: 20/Mar/18 11:23
• Updated: 28/Aug/22 15:27
• Resolved: 23/Feb/19 14:25

Description

I'd like Lucene to have better support for scoring across multiple fields. Today we have BlendedTermQuery which tries to help there but it probably tries to do too much on some aspects (handling cross-field term queries AND synonyms) and too little on other ones (it tries to merge index-level statistics, but not per-document statistics like tf and norm).

Maybe we could implement something like BM25F so that queries across multiple fields would retain the benefits of BM25 like the fact that the impact of the term frequency saturates quickly, which is not the case with BlendedTermQuery if you have occurrences across many fields.