Adrien Grand created LUCENE-8197:
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Summary: Make top-k queries fast when static scoring signals are
incorporated into the score
Key: LUCENE-8197
URL: https://issues.apache.org/jira/browse/LUCENE-8197
Project: Lucene - Core
Issue Type: Improvement
Reporter: Adrien Grand
Fix For: master (8.0)
Block-max WAND (LUCENE-8135) and some earlier issues made Lucene faster at
computing the top-k matches of boolean queries.
It is quite frequent that users want to improve ranking and end up scoring with
a formula that could look like {{bm25_score + w * log(alpha + pagerank)}} (w
and alpha being constants, and pagerank being a per-document field value). You
could do this with doc values and {{FunctionScoreQuery}} but unfortunately this
will remove the ability to optimize top-k queries since the scoring formula
becomes opaque to Lucene.
I'd like to add a new field that allows to store such scoring signals as term
frequencies, and new queries that could produce {{log(alpha + pagerank)}} as a
score. Then implementing the above formula can be done by boosting this query
with a boost equal to {{w}} and adding this boosted query as a SHOULD clause of
a {{BooleanQuery}}. This would give Lucene the ability to compute top-k hits
faster, especially but not only if the index is sorted by decreasing pagerank.
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