[
https://issues.apache.org/jira/browse/LUCENE-4396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13940342#comment-13940342
]
Da Huang commented on LUCENE-4396:
----------------------------------
Hi, Mike.
I have just finished revising my proposal. I'm not so sure about the decription
on this page "unless the MUST clauses have very low hit count compared to the
other clauses, that BooleanScorer would perform better than BooleanScorer2.".
In my opinion, even when MUST clauses have very low hit count compared to the
other clauses, BooleanScorer is likely to perform better than BooleanScorer2,
because the calling on .advance() when dealing with SHOULD clauses can skip
documents as many as BooleanScorer2 does.
Relevant ideas is described in the session "Improve the Rule for Choosing
Scorer". As it's not very consistent with the description on this page, I'm not
sure whether my idea makes sense.
> 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
>
> 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!
--
This message was sent by Atlassian JIRA
(v6.2#6252)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
