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https://issues.apache.org/jira/browse/LUCENE-6276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14989595#comment-14989595
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Adrien Grand commented on LUCENE-6276:
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- can you add to the javadocs of TwoPhaseIterator#matchCost that match costs
need to be a positive number?
- can you add some comments around the cost computation for
disjunctions/conjunctions to explain the reasoning?
- I would prefer termPositionsCost to be duplicated in PhraseWeight and
SpanNearQuery than in TwoPhaseIterator, like we do for disjunctions
(SpanOrQuery and DisjunctionScorer). I can understand the concerns around
duplication but I think it's still cleaner than trying to share the logic by
adding utility methods to TwoPhaseIterator.
- I think SpanTermQuery.PHRASE_TO_SPAN_TERM_POSITIONS_COST should be static?
Otherwise the change looks good to me, I like the cost definition for
conjunctions/disjunctions/phrases and we can tackle other queries in follow-up
issues, but I think this is already a great start and will help execute slow
queries more efficiently!
> 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, 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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