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https://issues.apache.org/jira/browse/LUCENE-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13063644#comment-13063644
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Grant Ingersoll commented on LUCENE-2878:
-----------------------------------------
bq. I'm not sure this sounds like an inverted index is even the best data
structure for what you describe
The key is you usually have a fairly complex Query to begin with, so I do think
it is legitimate and it is the right data structure. It is always driven by
the search results. I've seen this use case multiple times, where multiple is
more than 10, so I am pretty convinced it is beyond just me. I think if you
are taking away the ability to create windows around a match (if you read my
early comments on this issue I brought it up from the beginning), that is a
pretty big loss. I don't think the two things are mutually exclusive. As long
as I have a way to get at the positions for all matches, I don't care that it.
A "collector" type callback interface or a way for one to iterate all positions
for a given match should be sufficient.
That being said, if Mike's comments about a collector like API are how it is
implemented, I think it should work. In reality, I think one would just need a
way to, for whatever number of results, be told about positions as they happen.
Naturally, the default should be to only do this after the top X are
retrieved, when X is small, but I could see implementing it in the scoring loop
on certain occasions (and I'm not saying Lucene need have first order support
for that). As long as you don't preclude me from doing that, it should be fine.
I'll try to find time to review the patch in more depth in the coming day or so.
> 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: Bulk Postings branch
> Reporter: Simon Willnauer
> Assignee: Simon Willnauer
> Labels: gsoc2011, lucene-gsoc-11, mentor
> 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_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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