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From Erik Hatcher <e...@ehatchersolutions.com>
Subject Re: Wildcard and Fuzzy queries - no best fragments generated - ??
Date Wed, 28 Dec 2005 01:21:57 GMT

On Dec 27, 2005, at 5:51 PM, Dmitry Goldenberg wrote:
> This is great.  Now, just so I understand how rewrite applies.  Are  
> there specific cases when the rewrite method should or should not  
> be invoked on the query before it is passed on to the search  
> method?  Where I'm going with this is, if I have a UI which passes  
> the user query to the back end, can the back end always call  
> rewrite or not?
> By looking at the code, it seems that things just get reinterpreted  
> as BooleanQuery's and such.  I just want to know if there are any  
> pitfalls to watch out for.

It is safe, and wise, to always call Query.rewrite before  
highlighting.  No worries or pitfalls that I know of.

	Erik



>
> Thanks again,
> - Dmitry
>
> ________________________________
>
> From: Erik Hatcher [mailto:erik@ehatchersolutions.com]
> Sent: Tue 12/27/2005 12:13 PM
> To: java-user@lucene.apache.org
> Subject: Re: Wildcard and Fuzzy queries - no best fragments  
> generated - ??
>
>
>
>
> On Dec 27, 2005, at 2:34 PM, Dmitry Goldenberg wrote:
>> What do you mean by _rewriting_ the query?  I checked all the
>> classes in the highlighter package and did not see any mention of
>> having to rewrite.
>
>  From Highlighter's package.html in it's javadocs:
>
> <pre>
>         IndexSearcher searcher = new IndexSearcher(ramDir);
>         Query query = QueryParser.parse("Kenne*", FIELD_NAME,  
> analyzer);
>         query = query.rewrite(reader); //required to expand search  
> terms
>         Hits hits = searcher.search(query);
>
>         Highlighter highlighter = new Highlighter(this, new  
> QueryScorer
> (query));
>         for (int i = 0; i &lt; hits.length(); i++)
>         {
>                 String text = hits.doc(i).get(FIELD_NAME);
>                 TokenStream tokenStream = analyzer.tokenStream 
> (FIELD_NAME, new
> StringReader(text));
>                 // Get 3 best fragments and seperate with a "..."
>                 String result = highlighter.getBestFragments 
> (tokenStream, text, 3,
> "...");
>                 System.out.println(result);
>         }
> </pre>
>
>
>
>
>
>> ________________________________
>>
>> From: Erik Hatcher [mailto:erik@ehatchersolutions.com]
>> Sent: Tue 12/27/2005 11:03 AM
>> To: java-user@lucene.apache.org
>> Subject: Re: Wildcard and Fuzzy queries - no best fragments
>> generated - ??
>>
>>
>>
>> You have to _rewrite_ the Query for this to work.  This, I believe,
>> is mentioned in the javadocs.
>>
>> I think you are hijacking a thread with your recent postings.  Please
>> create a new message rather than reply to one and change the
>> subject.  Thanks.
>>
>>         Erik
>>
>>
>> On Dec 27, 2005, at 1:55 PM, Dmitry Goldenberg wrote:
>>
>>> Hello,
>>>
>>> While testing my code that integrates the Highlighter class from
>>> org.apache.lucene.search.highlight, I found out that for wildcard
>>> and fuzzy queries, it generates no best fragments.
>>>
>>> Any particular reason why that is the case?  Shouldn't the
>>> highlighter be able to work just like with any other query and
>>> highlight any matching token sequences?  E.g. if I'm searching for
>>> lava~, I'd expect it to highlight words like lava, java, etc.  This
>>> is the whole point of highlighting, is it not?
>>>
>>> Thanks,
>>> - Dmitry
>>>
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>>
>>
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>
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