[LUCENE-1302] explain should not mask negative scores

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Invalid
• Fix Version/s: 2.4
• Component/s: core/query/scoring
• Lucene Fields: Patch Available
• Assignee: Doron Cohen
• Reporter: Doron Cohen
• Created: 10/Jun/08 13:09
• Updated: 28/Aug/22 11:50
• Resolved: 10/Jun/08 19:50

Description

Explanation.isMatch() returns false for 0 or negative scores.
Hence negative scores are omitted from the explanation.
This causes, when using e.g. BoostingTermQuery with negative boosts, a difference between the collected doc score and the score shown by explain().

A word on the usage of this - BTQ with negative boosts is useful for "punishing" documents for containing a term. It also allows all sorts of tricks with multiplying query boost by the BTQ boost, so you get a positive score if both boosts have the same sign but negative otherwise. - I am sure there other uses as well.