[LUCENE-2880] SpanQuery scoring inconsistencies

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.3
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Robert Muir
• Created: 23/Jan/11 15:08
• Updated: 28/Aug/22 12:39
• Resolved: 18/Jun/15 20:51

Description

Spinoff of LUCENE-2879.

You can see a full description there, but the gist is that SpanQuery sums up freqs with "sloppyFreq".
However this slop is simply spans.end() - spans.start()

For a SpanTermQuery for example, this means its scoring 0.5 for TF versus TermQuery's 1.0.
As you can imagine, I think in practical situations this would make it difficult for SpanQuery users to
really use SpanQueries for effective ranking, especially in combination with non-Spanqueries (maybe via DisjunctionMaxQuery, etc)

The problem is more general than this simple example: for example SpanNearQuery should be consistent with PhraseQuery's slop.

Issue Links

• is related to: LUCENE-533 SpanQuery scoring: SpanWeight lacks a recursive traversal of the query tree