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https://issues.apache.org/jira/browse/LUCENE-6198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14289874#comment-14289874
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Yonik Seeley commented on LUCENE-6198:
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I wonder if there's any way to provide more context so that approximations can 
be adjusted/tuned.
As an example, for an exact phrase match like "the zoo", I imagine it would 
often be a win to just use the docsenum for "zoo" as the approximation.  But as 
a generalization it would seem to matter what else was in the conjunction and 
how expensive they are.

> two phase intersection
> ----------------------
>
>                 Key: LUCENE-6198
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6198
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Robert Muir
>         Attachments: LUCENE-6198.patch
>
>
> 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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