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https://issues.apache.org/jira/browse/LUCENE-6276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14962547#comment-14962547
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Paul Elschot commented on LUCENE-6276:
--------------------------------------
Another thing to be determined is this the relative cost of span queries vs
phrase queries.
The code for that is in SpanTermQuery here:
{code}
/** A guess of
* the relative cost of dealing with the term positions
* when using a SpanNearQuery instead of a PhraseQuery.
*/
private final float PHRASE_TO_SPAN_TERM_POSITIONS_COST = 4.0f;
{code}
This is a guess because it is only based on my recollection of a few years ago
of that performance of PhraseQuery was about 4 times as fast as an ordered
SpanNear.
In the long term it is probably better to make this a configurable parameter.
> Add matchCost() api to TwoPhaseDocIdSetIterator
> -----------------------------------------------
>
> Key: LUCENE-6276
> URL: https://issues.apache.org/jira/browse/LUCENE-6276
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Robert Muir
> Attachments: LUCENE-6276-ExactPhraseOnly.patch,
> LUCENE-6276-NoSpans.patch, LUCENE-6276-NoSpans2.patch, LUCENE-6276.patch,
> LUCENE-6276.patch, LUCENE-6276.patch, LUCENE-6276.patch
>
>
> We could add a method like TwoPhaseDISI.matchCost() defined as something like
> estimate of nanoseconds or similar.
> ConjunctionScorer could use this method to sort its 'twoPhaseIterators' array
> so that cheaper ones are called first. Today it has no idea if one scorer is
> a simple phrase scorer on a short field vs another that might do some geo
> calculation or more expensive stuff.
> PhraseScorers could implement this based on index statistics (e.g.
> totalTermFreq/maxDoc)
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