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https://issues.apache.org/jira/browse/LUCENE-4396?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Da Huang updated LUCENE-4396:
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Attachment: AndOr.tasks
luceneutil tasks file to test queries like "+a b c d e ..."
The performance shows as follows.
TaskQPS baseline StdDevQPS my_modified_version
StdDev Pct diff
HighAndManyLowOr 8.50 (3.3%) 1.72 (0.3%)
-79.8% ( -80% - -78%)
PKLookup 239.75 (0.9%) 239.99 (0.9%)
0.1% ( -1% - 1%)
LowAndManyHighOr 7.11 (1.4%) 7.76 (1.4%)
9.1% ( 6% - 12%)
LowAndManyLowOr 33.83 (0.7%) 41.03 (2.7%)
21.3% ( 17% - 24%)
HighAndManyHighOr 0.12 (0.7%) 0.29 (7.8%)
148.0% ( 138% - 157%)
> 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
>
>
> 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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