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From "Robert Muir (JIRA)" <>
Subject [jira] [Commented] (LUCENE-4825) PostingsHighlighter support for positional queries
Date Tue, 12 Mar 2013 20:01:12 GMT


Robert Muir commented on LUCENE-4825:

I think it supports positional queries, just in a different way. 

I don't really like the way the standardhighlighter does this myself. I would prefer if we
avoided the slow stuff
those things do in this highlighter (because we already have other ones that do that). This
one instead puts more effort
on trying to summarize the document with respect to the query terms (which is faster, and
for some cases, better use of cpu time).

I think a good improvement would be to letting the proximity of terms within passages influence
the scoring. Its not necessary to actually gather anything about the query to do this and
wouldnt be confusing and would still support all queries that support extractTerms().

On the other hand we can always create variants of this highlighter that do as you suggest,
so that it leaves the user with more choices. But I just would prefer we don't try to force
PostingsHighlighter work like the other highlighters for the reasons i mentioned.

> PostingsHighlighter support for positional queries
> --------------------------------------------------
>                 Key: LUCENE-4825
>                 URL:
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: modules/highlighter
>    Affects Versions: 4.2
>            Reporter: Luca Cavanna
> I've been playing around with the brand new PostingsHighlighter. I'm really happy with
the result in terms of quality of the snippets and performance.
> On the other hand, I noticed it doesn't support positional queries. If you make a span
query, for example, all the single terms will be highlighted, even though they haven't contributed
to the match. That reminds me of the difference between the QueryTermScorer and the QueryScorer
(using the standard Highlighter).
> I've been trying to adapt what the QueryScorer does, especially the extraction of the
query terms together with their positions (what WeightedSpanTermExtractor does). Next step
would be to take that information into account within the formatter and highlight only the
terms that actually contributed to the match. I'm not quite ready yet with a patch to contribute
this back, but I certainly intend to do so. That's why I opened the issue and in the meantime
I would like to hear what you guys think about it and  discuss how best we can fix it. I think
it would be a big improvement for this new highlighter, which is already great!

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