Hey everyone, I have a question about Lucene/Solr scoring in general. It really feels like a wobbly house of cards that falls down whenever I make the slightest tweak. There are many factors at play in Lucene scoring: they're all fighting with each other, and very often one will completely dominate everything else, when that may not really be the intention.
** The question: might there be a way to enforce strict requirements that certain factors are higher priority than other factors, and/or certain factors shouldn't overtake other factors? Perhaps a set of rules where one factor is considered before even examining another factor? Tuning boost numbers around and hoping for the best seems imprecise and very fragile. ** To make this more concrete, an example: We previously added the scores of multi-field matches together via an OR, so: score(query "apple") = score(field1:apple) + score(field2:apple). I changed that to be more in-line with DisMaxParser, namely a max: score(query "apple") = max(score(field1:apple), score(field2:apple)). I also modified coord such that coord would only consider actual unique terms ("apple" vs. "orange"), rather than terms across multiple fields (field1:apple vs. field2:apple). This seemed like a good idea, but it actually introduced a bug that was previously hidden. Suddenly, documents matching "apple" in the title and *nothing* in the body were being boosted over "apple" in the title and "apple" in the body! I investigated, and it was due to lengthNorm: previously, documents matching "apple" in both title and body were getting higher scores thanks to to summing the field scores (vs. max) as well as a higher coord score. Now that they were no longer getting these boosts, which was beneficial in many respects, the playing field was leveled. And this leveling of the playing field allowed lengthNorm to dominate everything else. Any help would be much appreciated. Thanks! Tavi -- View this message in context: http://lucene.472066.n3.nabble.com/Scoring-Precedent-for-a-Better-Less-Fragile-Approach-tp2445112p2445112.html Sent from the Lucene - Java Developer mailing list archive at Nabble.com. --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org