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From "Hoss Man (JIRA)" <j...@apache.org>
Subject [jira] Commented: (SOLR-1954) Highlighter component should expose snippet character offsets and the score.
Date Fri, 18 Jun 2010 22:44:23 GMT

    [ https://issues.apache.org/jira/browse/SOLR-1954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12880350#action_12880350
] 

Hoss Man commented on SOLR-1954:
--------------------------------

{quote}
1) isn't highlighting fairly fundamentally character based? would you ever want/expect a highlight
position to be based on bytes that break up a logical character?
2) being largely ignorant of highlighting, i would say the units should be in whatever the
Highlighter currently use when indexing into string values - my understanidng is that it's
the same as the start/end offsets in tokens, so if they are char then it's char, if they are
bytes, then it's bytes.
{quote}

On IRC rmuir convinced me that the world is not this simple ... char offsets makes sense when
dealing just with the java API, but once you send the data over the wire to a remote client,
it might be using any arbitrary charset in memory, so the only possible unit you can use to
convey position information that can be ignorant of the remote client is bytes.

> Highlighter component should expose snippet character offsets and the score.
> ----------------------------------------------------------------------------
>
>                 Key: SOLR-1954
>                 URL: https://issues.apache.org/jira/browse/SOLR-1954
>             Project: Solr
>          Issue Type: New Feature
>          Components: highlighter
>            Reporter: David Smiley
>            Priority: Minor
>         Attachments: SOLR-1954_start_and_end_offsets.patch
>
>
> The Highlighter Component does not currently expose the snippet character offsets nor
the score.  There is a TODO in DefaultSolrHighlighter indicating the intention to add this
eventually.  This information is needed when doing highlighting on external content.  The
data is there so its pretty easy to output it in some way.  The challenge is deciding on the
output and its ramifications on backwards compatibility.  The current highlighter component
response structure doesn't lend itself to adding any new data, unfortunately.  I wish the
original implementer had some foresight.  Unfortunately all the highlighting tests assume
this structure.  Here is a snippet of the current response structure in Solr's sample data
searching for "sdram" for reference:
> {code:xml}
> <lst name="highlighting">
>  <lst name="VS1GB400C3">
>   <arr name="text">
> 	<str>CORSAIR ValueSelect 1GB 184-Pin DDR &lt;em&gt;SDRAM&lt;/em&gt;
Unbuffered DDR 400 (PC 3200) System Memory - Retail</str>
>   </arr>
>  </lst>
> </lst>
> {code}
> Perhaps as a little hack, we introduce a pseudo field called text_startCharOffset which
is the concatenation of the matching field and "_startCharOffset".  This would be an array
of ints.  Likewise, there would be another array for endCharOffset and score.
> Thoughts?

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