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From Donna L Gresh <gr...@us.ibm.com>
Subject Re: Question about highlighting returning nothing
Date Thu, 16 Aug 2007 13:25:35 GMT
Actually I don't think I'm having trouble-- as I mentioned,
my text is *not* stored, so to do highlighting I retrieve the
text from the database, apply the appropriate analyzer, 
and do the highlighting. It seems to be working exactly as
it should. My problem was that in a few cases, the document
has been removed from the database (but not from the index)
so when I queried the database using the identifier for the "best
hit" from the index, nothing
was being returned. Passing "nothing" to the highlighter 
resulted in, of course, nothing, so I was getting no highlighted
text. Once I updated my index to be in synch with the database,
I no longer had any empty returns from the highlighter.

Donna L. Gresh
Services Research, Mathematical Sciences Department
IBM T.J. Watson Research Center
(914) 945-2472
http://www.research.ibm.com/people/g/donnagresh
gresh@us.ibm.com




"Lukas Vlcek" <lukas.vlcek@gmail.com> 
08/15/2007 03:49 PM
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Subject
Re: Question about highlighting returning nothing






Donna,

I have been investigation highlighters in Lucene recently a bit. The 
humble
experience I've learned so far is that highlighting is completely 
different
task from indexing/searching tandem. This simple fact is not obvious to a
lot of people. In your particular casue it would be helpful if you can 
post
more technical details about your system settings. Not only it is 
important
if the field to be highlighted is stored but also it is important if you
allow for query rewrite and what king of queries you are using (Prefix,
Wildcard ... etc).

Just my 2 cents.

Lukas

On 8/15/07, Donna L Gresh <gresh@us.ibm.com> wrote:
>
> Well, in my case the highlighting was returning nothing because of (my
> favorite acronym) PBCAK--
>
> I don't store the text in the index, so I have to retrieve it separately
> (from a database) for the highlighting, and my database was not in sync
> with the index, so in a few cases the document in the index had been
> deleted from the database--thus a score, but no document text.
>
> But I guess my original question remains; under what conditions would 
the
> highlighter return nothing? Only if no terms matched?
>
> Donna
>


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