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https://issues.apache.org/jira/browse/LUCENE-7421?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Adrien Grand closed LUCENE-7421.
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Resolution: Won't Fix
Hmm actually it helps less (only 2-3%) when the boolean query is nested under a
conjunction (which is typically how BS2 gets used), so this is probably not
that interesting.
{noformat}
AndMedOrHighLow 22.62 (2.3%) 23.24 (2.3%)
2.7% ( -1% - 7%)
{noformat}
> Speed up BS2 by caching the 2nd lowest doc id in the priority queue
> -------------------------------------------------------------------
>
> Key: LUCENE-7421
> URL: https://issues.apache.org/jira/browse/LUCENE-7421
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Adrien Grand
> Assignee: Adrien Grand
> Priority: Minor
> Attachments: LUCENE-7421.patch
>
>
> BS2 uses a priority queue in order to merge several sorted iterators into a
> new sorted iterator. We call updateTop every time that we move the 'top'
> iterator forward, which requires to check the size of the priority queue at
> least twice and perform at least two comparisons of doc ids.
> Instead, DisjunctionSumScorer could cache the 2nd lowest doc id of the
> priority queue and only call updateTop when the doc id of the entry at the
> top of the priority queue goes beyong the 2nd lowest doc id. While this would
> involve slightly more work in the case that the PQ has two high-cardinality
> clauses whose docs are interleaved, this would help when one clause has a
> much higher cardinality than the other ones or when the doc ids of the
> various clauses are clustered.
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