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From "Paul Elschot (JIRA)" <>
Subject [jira] Commented: (LUCENE-1252) Avoid using positions when not all required terms are present
Date Thu, 23 Apr 2009 15:05:30 GMT


Paul Elschot commented on LUCENE-1252:

There is no patch for now.

HitCollectors should not be affected by this, as they would only be involved when a real match
is found, and that, when position info is needed, necessarily involves the positions.

Extending this with a cheap score brings another issue: should a cheap score be given for
a document that might match, but in the end does not really match when positions are used?
At the moment, I don't think so: score values are normally cheap to compute, but accessing
positions is not cheap.

> Avoid using positions when not all required terms are present
> -------------------------------------------------------------
>                 Key: LUCENE-1252
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Wish
>          Components: Search
>            Reporter: Paul Elschot
>            Priority: Minor
> In the Scorers of queries with (lots of) Phrases and/or (nested) Spans, currently next()
and skipTo() will use position information even when other parts of the query cannot match
because some required terms are not present.
> This could be avoided by adding some methods to Scorer that relax the postcondition of
next() and skipTo() to something like "all required terms are present, but no position info
was checked yet", and implementing these methods for Scorers that do conjunctions: BooleanScorer,
PhraseScorer, and SpanScorer/NearSpans.

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