[
https://issues.apache.org/jira/browse/LUCENENET-288?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Garski updated LUCENENET-288:
-------------------------------------
Attachment: ExplanationComparison.txt
LUCENENET-288.patch
The root cause of the issue IS a floating point arithmetic issue.
The tests in TestCustomScoreQuery exercise a few custom function queries and
then compare the score from the scorer to the score from the explanation. The
tolerance factor in the Java code base is used to account for floating point
discrepancies as the scorer and explanation may perform the calculation in
different orders.
There are several sub-tests occurring within the test, once with the test index
created that consists of 17 documents, and others with wrapped indexes that
have deleted documents in them, changing the IDF value of the score due to the
different value of MaxDocs(). It's the changed IDF value in combination with
the query boosts that throw the score differences outside the range of the
tolerance. I modified the test to not add the document deletions and
everything passes. I reverted the test and then modified the tests to only use
query boosts of 2.0 or less and everything passes.
I wanted to compare the results to what was happening in the JUnit tests, so I
found the NUnit case that had the greatest delta between the two scores and
compared it to the same case in JUnit (file showing the two comparisons is
attached). The differences are very minor due to floating point precision, and
I feel that altering the tolerance value of
CheckHits.EXPLAIN_SCORE_TOLERANCE_DELTA to 0.00025f, a value that is 5 times
greater than in Java, is acceptable. The attached patch does nothing more than
alter that tolerance value.
I spent yesterday afternoon and this morning going through this issue as
CustomScoreQuery is of particular importance to me as we use this internally to
customize scoring for social relevancy of a particular item.
If anyone is uncomfortable with the tolerance change feel free to investigate
and propose another solution.
> Function.TestCustomScoreQuery
> -----------------------------
>
> Key: LUCENENET-288
> URL: https://issues.apache.org/jira/browse/LUCENENET-288
> Project: Lucene.Net
> Issue Type: Bug
> Reporter: Michael Garski
> Attachments: ExplanationComparison.txt, LUCENENET-288.patch
>
>
> Three of the tests in TestCustomScoreQuery are not passing due to the
> comparison between the explanation score and the hit score do not fall within
> the tolerance of +-0.00005f. Altering the tolerance to 0.0005f causes all of
> the tests to pass, so there appears to be a subtle issue in how the scores
> are being calculated.
> A similar test exists in 2.4 that passes with the tolerance of 0.00005f,
> which to me rules out floating point calculation differences.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
