On: BM25 – The Next Generation of Lucene Relevance

[asjo]

Xapian has been using BM25 forever[1] - what made Lucene switch now?

[1] https://xapian.org/docs/bm25.html

[apatry → asjo]

BM25 has been available for Lucene since version 4 thanks to a refactoring that allowed anyone to plug in a custom relevance score if I remember correctly . The big news is that starting version 6, BM25 is the default.

[asjo → apatry]

Yes, so I am asking why is Lucene switching now?

[nl → asjo]

Here's the issue tracking[1].

Basically it looks like the typical conservative approach most large scale open source projects are forced to take because of cross dependencies.

It's a (potentially) breaking change, so they waited for a major release.

[1] https://issues.apache.org/jira/browse/LUCENE-6789