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https://issues.apache.org/jira/browse/LUCENE-1522?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12682351#action_12682351
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Koji Sekiguchi commented on LUCENE-1522:
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{quote}
Actually I was asking whether every fragment that's returned is
guaranteed to show a match to my original query.
EG if my query is a PhraseQuery, is it guaranteed that all fragments
presented are valid matches? If I search for "Alan Greenspan's
mortgage", is it ever possible to see a fragment that contains only
"Alan Greenspan"?
{quote}
I see. Yes, H2 guarantees it.
{quote}
OK so eg *SpanQuery won't work? It seems like both highlighters take
this "flatten" approach, which can lose the constraints for
interesting queries (like Span, or a custom query).
{quote}
H2 doesn't support SpanQuery right now. I'll look at SpanScorer and LUCENE-1425
to see whether I can support "interesting queries" in H2, before going to
"eventual model" (looks great) you mentioned above.
> another highlighter
> -------------------
>
> Key: LUCENE-1522
> URL: https://issues.apache.org/jira/browse/LUCENE-1522
> Project: Lucene - Java
> Issue Type: Improvement
> Components: contrib/highlighter
> Reporter: Koji Sekiguchi
> Assignee: Michael McCandless
> Priority: Minor
> Fix For: 2.9
>
> Attachments: colored-tag-sample.png, LUCENE-1522.patch,
> LUCENE-1522.patch
>
>
> I've written this highlighter for my project to support bi-gram token stream
> (general token stream (e.g. WhitespaceTokenizer) also supported. see test
> code in patch). The idea was inherited from my previous project with my
> colleague and LUCENE-644. This approach needs highlight fields to be
> TermVector.WITH_POSITIONS_OFFSETS, but is fast and can support N-grams. This
> depends on LUCENE-1448 to get refined term offsets.
> usage:
> {code:java}
> TopDocs docs = searcher.search( query, 10 );
> Highlighter h = new Highlighter();
> FieldQuery fq = h.getFieldQuery( query );
> for( ScoreDoc scoreDoc : docs.scoreDocs ){
> // fieldName="content", fragCharSize=100, numFragments=3
> String[] fragments = h.getBestFragments( fq, reader, scoreDoc.doc,
> "content", 100, 3 );
> if( fragments != null ){
> for( String fragment : fragments )
> System.out.println( fragment );
> }
> }
> {code}
> features:
> - fast for large docs
> - supports not only whitespace-based token stream, but also "fixed size"
> N-gram (e.g. (2,2), not (1,3)) (can solve LUCENE-1489)
> - supports PhraseQuery, phrase-unit highlighting with slops
> {noformat}
> q="w1 w2"
> <b>w1 w2</b>
> ---------------
> q="w1 w2"~1
> <b>w1</b> w3 <b>w2</b> w3 <b>w1 w2</b>
> {noformat}
> - highlight fields need to be TermVector.WITH_POSITIONS_OFFSETS
> - easy to apply patch due to independent package (contrib/highlighter2)
> - uses Java 1.5
> - looks query boost to score fragments (currently doesn't see idf, but it
> should be possible)
> - pluggable FragListBuilder
> - pluggable FragmentsBuilder
> to do:
> - term positions can be unnecessary when phraseHighlight==false
> - collects performance numbers
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