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https://issues.apache.org/jira/browse/LUCENE-4396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14079117#comment-14079117
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Michael McCandless commented on LUCENE-4396:
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bq. It makes me embarrassed that I'm not able to get the cost of a scorer
without an instance of Scorer.
Hmm, maybe BulkScorer should also have a cost method?
bq. Besides, I'm very sorry that the code in this patch may looks ugly, as I
haven't spared enough time to rearrange the code.
No worries, this is perfectly normal and healthy in iterative open-source
development! This is just how the iterations work...
bq. or the TestBooleanScorer.testEmbeddedBooleanScorer will throws an
UnsupportedOperationException because it calls an unimplemented .scorer()
method.
This test may simply be too ridiculous! It's just trying to ensure that we can
do the boolean bulk scoring embedded inside another bulk scorer.
> BooleanScorer should sometimes be used for MUST clauses
> -------------------------------------------------------
>
> Key: LUCENE-4396
> URL: https://issues.apache.org/jira/browse/LUCENE-4396
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Michael McCandless
> Attachments: And.tasks, AndOr.tasks, AndOr.tasks, LUCENE-4396.patch,
> LUCENE-4396.patch, LUCENE-4396.patch, LUCENE-4396.patch, LUCENE-4396.patch,
> LUCENE-4396.patch, LUCENE-4396.patch, LUCENE-4396.patch, LUCENE-4396.patch,
> LUCENE-4396.patch, LUCENE-4396.patch, SIZE.perf, all.perf,
> luceneutil-score-equal.patch, luceneutil-score-equal.patch, stat.cpp, stat.cpp
>
>
> Today we only use BooleanScorer if the query consists of SHOULD and MUST_NOT.
> If there is one or more MUST clauses we always use BooleanScorer2.
> But I suspect that unless the MUST clauses have very low hit count compared
> to the other clauses, that BooleanScorer would perform better than
> BooleanScorer2. BooleanScorer still has some vestiges from when it used to
> handle MUST so it shouldn't be hard to bring back this capability ... I think
> the challenging part might be the heuristics on when to use which (likely we
> would have to use firstDocID as proxy for total hit count).
> Likely we should also have BooleanScorer sometimes use .advance() on the subs
> in this case, eg if suddenly the MUST clause skips 1000000 docs then you want
> to .advance() all the SHOULD clauses.
> I won't have near term time to work on this so feel free to take it if you
> are inspired!
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