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From "Simon Willnauer (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-2878) Allow Scorer to expose positions and payloads aka. nuke spans
Date Wed, 11 Jul 2012 12:00:46 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13411425#comment-13411425
] 

Simon Willnauer commented on LUCENE-2878:
-----------------------------------------

hey alan,

I merged the branch up with trunk and applied you patch (latest-1). Your changes to PhraseQuery
are tricky. The SloppyPhraseScorer now uses the same DocsAndPosition enums as the PosIterator
in there. That is unfortunately not how it should be. If you pull a PosIterator from a scorer
there should not be any side-effect on the score or the iterator if you advance one or the
other. Currently I see a failure in PosHighlighterTest: 

{noformat}

[junit4:junit4] Suite: org.apache.lucene.search.poshighlight.PosHighlighterTest
[junit4:junit4] FAILURE 0.22s J0  | PosHighlighterTest.testSloppyPhraseQuery
[junit4:junit4]    > Throwable #1: java.lang.AssertionError: nextPosition() was called
too many times (more than freq() times) posPendingCount=-1
[junit4:junit4]    > 	at __randomizedtesting.SeedInfo.seed([C966081DA1EFC306:32134412A4F88738]:0)
[junit4:junit4]    > 	at org.apache.lucene.codecs.lucene40.Lucene40PostingsReader$SegmentFullPositionsEnum.nextPosition(Lucene40PostingsReader.java:1127)
[junit4:junit4]    > 	at org.apache.lucene.search.PhrasePositions.nextPosition(PhrasePositions.java:76)
[junit4:junit4]    > 	at org.apache.lucene.search.PhrasePositions.firstPosition(PhrasePositions.java:65)
[junit4:junit4]    > 	at org.apache.lucene.search.SloppyPhraseScorer.initSimple(SloppyPhraseScorer.java:230)
[junit4:junit4]    > 	at org.apache.lucene.search.SloppyPhraseScorer.initPhrasePositions(SloppyPhraseScorer.java:218)
[junit4:junit4]    > 	at org.apache.lucene.search.SloppyPhraseScorer.access$800(SloppyPhraseScorer.java:28)
[junit4:junit4]    > 	at org.apache.lucene.search.SloppyPhraseScorer$SloppyPhrasePositionIntervalIterator.advanceTo(SloppyPhraseScorer.java:533)
[junit4:junit4]    > 	at org.apache.lucene.search.poshighlight.PosCollector.collect(PosCollector.java:53)
[junit4:junit4]    > 	at org.apache.lucene.search.Scorer.score(Scorer.java:62)
[junit4:junit4]    > 	at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:574)
[junit4:junit4]    > 	at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:287)
[junit4:junit4]    > 	at org.apache.lucene.search.poshighlight.PosHighlighterTest.doSearch(PosHighlighterTest.java:161)
[junit4:junit4]    > 	at org.apache.lucene.search.poshighlight.PosHighlighterTest.doSearch(PosHighlighterTest.java:147)
[junit4:junit4]    > 	at org.apache.lucene.search.poshighlight.PosHighlighterTest.testSloppyPhraseQuery(PosHighlighterTest.java:378)
...
[junit4:junit4]   2> NOTE: reproduce with: ant test  -Dtestcase=PosHighlighterTest -Dtests.method=testSloppyPhraseQuery
-Dtests.seed=C966081DA1EFC306 -Dtests.slow=true -Dtests.locale=sr 
-Dtests.timezone=Africa/Harare -Dtests.file.encoding=UTF-8
[junit4:junit4]   2>
[junit4:junit4]    > (@AfterClass output)
[junit4:junit4]   2> NOTE: test params are: codec=Lucene40: {}, sim=RandomSimilarityProvider(queryNorm=true,coord=false):
{f=DFR I(ne)B3(800.0)}, locale=sr, timezone=Africa/Harare
[junit4:junit4]   2> NOTE: Linux 2.6.38-15-generic amd64/Sun Microsystems Inc. 1.6.0_26
(64-bit)/cpus=12,threads=1,free=327745216,total=379322368
[junit4:junit4]   2> NOTE: All tests run in this JVM: [PosHighlighterTest]
[junit4:junit4]   2> 

{noformat}

this makes the entire sloppy case very tricky though. Even further I don't think sloppy phrase
is really correct and if I recall correctly there some issue with it that haven't been resolved
for years now. I am not sure how we should proceed with that one. I will need to think about
that further.


bq. Next step is to try and reimplement the various SpanQuery tests using the position filter
queries in their place.

please go ahead!

                
> Allow Scorer to expose positions and payloads aka. nuke spans 
> --------------------------------------------------------------
>
>                 Key: LUCENE-2878
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2878
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: core/search
>    Affects Versions: Positions Branch
>            Reporter: Simon Willnauer
>            Assignee: Simon Willnauer
>              Labels: gsoc2011, gsoc2012, lucene-gsoc-11, lucene-gsoc-12, mentor
>             Fix For: Positions Branch
>
>         Attachments: LUCENE-2878-OR.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch,
LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch,
LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch,
LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch,
LUCENE-2878.patch, LUCENE-2878_trunk.patch, LUCENE-2878_trunk.patch, PosHighlighter.patch,
PosHighlighter.patch
>
>
> Currently we have two somewhat separate types of queries, the one which can make use
of positions (mainly spans) and payloads (spans). Yet Span*Query doesn't really do scoring
comparable to what other queries do and at the end of the day they are duplicating lot of
code all over lucene. Span*Queries are also limited to other Span*Query instances such that
you can not use a TermQuery or a BooleanQuery with SpanNear or anthing like that. 
> Beside of the Span*Query limitation other queries lacking a quiet interesting feature
since they can not score based on term proximity since scores doesn't expose any positional
information. All those problems bugged me for a while now so I stared working on that using
the bulkpostings API. I would have done that first cut on trunk but TermScorer is working
on BlockReader that do not expose positions while the one in this branch does. I started adding
a new Positions class which users can pull from a scorer, to prevent unnecessary positions
enums I added ScorerContext#needsPositions and eventually Scorere#needsPayloads to create
the corresponding enum on demand. Yet, currently only TermQuery / TermScorer implements this
API and other simply return null instead. 
> To show that the API really works and our BulkPostings work fine too with positions I
cut over TermSpanQuery to use a TermScorer under the hood and nuked TermSpans entirely. A
nice sideeffect of this was that the Position BulkReading implementation got some exercise
which now :) work all with positions while Payloads for bulkreading are kind of experimental
in the patch and those only work with Standard codec. 
> So all spans now work on top of TermScorer ( I truly hate spans since today ) including
the ones that need Payloads (StandardCodec ONLY)!!  I didn't bother to implement the other
codecs yet since I want to get feedback on the API and on this first cut before I go one with
it. I will upload the corresponding patch in a minute. 
> I also had to cut over SpanQuery.getSpans(IR) to SpanQuery.getSpans(AtomicReaderContext)
which I should probably do on trunk first but after that pain today I need a break first :).
> The patch passes all core tests (org.apache.lucene.search.highlight.HighlighterTest still
fails but I didn't look into the MemoryIndex BulkPostings API yet)

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