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https://issues.apache.org/jira/browse/LUCENE-6198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14378276#comment-14378276
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David Smiley commented on LUCENE-6198:
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Having seen the TwoPhaseIterator in use and coded to its API, I think there is
room for streamlining it a bit. Almost all implementations have an
approximation() method that returns a DISI that was already constructed, and
the couple that don't are simple constructors to a DISI anyway. Well then
TwoPhaseIterator could take it in its constructor, put it on a field, and then
return it from approximation() as a default implementation.
TwoPhaseIterator's javadocs should make a reference to
Scorer.asTwoPhaseIterator.
Why is Scorer.asTwoPhaseIterator on Scorer and not DocIdSetIterator? It would
make this capability more general.
> two phase intersection
> ----------------------
>
> Key: LUCENE-6198
> URL: https://issues.apache.org/jira/browse/LUCENE-6198
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Robert Muir
> Assignee: David Smiley
> Fix For: Trunk, 5.1
>
> Attachments: LUCENE-6198.patch, LUCENE-6198.patch, LUCENE-6198.patch,
> LUCENE-6198.patch, LUCENE-6198.patch, phrase_intersections.tasks
>
>
> Currently some scorers have to do a lot of per-document work to determine if
> a document is a match. The simplest example is a phrase scorer, but there are
> others (spans, sloppy phrase, geospatial, etc).
> Imagine a conjunction with two MUST clauses, one that is a term that matches
> all odd documents, another that is a phrase matching all even documents.
> Today this conjunction will be very expensive, because the zig-zag
> intersection is reading a ton of useless positions.
> The same problem happens with filteredQuery and anything else that acts like
> a conjunction.
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