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Posted to dev@lucene.apache.org by "Yonik Seeley (JIRA)" <ji...@apache.org> on 2005/12/07 18:50:08 UTC
[jira] Resolved: (LUCENE-469) (Parallel-)MultiSearcher: using Sort object changes the scores
[ http://issues.apache.org/jira/browse/LUCENE-469?page=all ]
Yonik Seeley resolved LUCENE-469:
---------------------------------
Fix Version: 1.9
Resolution: Fixed
Assign To: Yonik Seeley
Fixed a small bug in the test (passing a null analyzer which causes a NPE with the new getPositionIncrement code), and committed.
Thanks Luke!
> (Parallel-)MultiSearcher: using Sort object changes the scores
> --------------------------------------------------------------
>
> Key: LUCENE-469
> URL: http://issues.apache.org/jira/browse/LUCENE-469
> Project: Lucene - Java
> Type: Bug
> Components: Search
> Versions: CVS Nightly - Specify date in submission
> Environment: 21 november 2005, revision 345901
> Reporter: Luc Vanlerberghe
> Assignee: Yonik Seeley
> Fix For: 1.9
> Attachments: MultiSearcherSort.patch, MultiSearcherSort.patch, TestMultiSearcher.patch
>
> Example:
> Hits hits=multiSearcher.search(query);
> returns different scores for some documents than
> Hits hits=multiSearcher.search(query, Sort.RELEVANCE);
> (both for MultiSearcher and ParallelMultiSearcher)
> The documents returned will be the same and in the same order, but the scores in the second case will seem out of order.
> Inspecting the Explanation objects shows that the scores themselves are ok, but there's a bug in the normalization of the scores.
> The document with the highest score should have score 1.0, so all document scores are divided by the highest score. (Assuming the highest score was>1.0)
> However, for MultiSearcher and ParallelMultiSearcher, this normalization factor is applied *per index*, before merging the results together (the merge itself is ok though).
> An example: if you use
> Hits hits=multiSearcher.search(query, Sort.RELEVANCE);
> for a MultiSearcher with two subsearchers, the first document will have score 1.0.
> The next documents from the same subsearcher will have decreasing scores.
> The first document from the other subsearcher will however have score 1.0 again !
> The same applies for other Sort objects, but it is less visible.
> I will post a TestCase demonstrating the problem and suggested patches to solve it in a moment...
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