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From "Da Huang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4396) BooleanScorer should sometimes be used for MUST clauses
Date Tue, 20 May 2014 00:13:38 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14002620#comment-14002620
] 

Da Huang commented on LUCENE-4396:
----------------------------------

Oh, thanks. I think it‘s worth a try.

> 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: AndOr.tasks, LUCENE-4396.patch, LUCENE-4396.patch, LUCENE-4396.patch,
LUCENE-4396.patch, luceneutil-score-equal.patch
>
>
> 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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