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From eks dev <eks...@yahoo.co.uk>
Subject Re: TSDC, TopFieldCollector & co
Date Wed, 30 Sep 2009 10:57:11 GMT
and another question, is it somehow possible to reuse TopScoreDocCollector instance? 

Javadoc in create(...) warns about allocating full array. 

<p><b>NOTE</b>: The instances returned by this method
   * pre-allocate a full array of length
   * <code>numHits</code>, and fill the array with sentinel
   * objects.
 





----- Original Message ----
> From: eks dev <eksdev@yahoo.co.uk>
> To: java-user@lucene.apache.org
> Sent: Wednesday, 30 September, 2009 11:43:26
> Subject: TSDC, TopFieldCollector & co
> 
> Hi All, 
> 
> What is the best way to achieve the following and what are the differences, if I 
> say "I do not normalize scores, so I do not need max score tracking, I do not 
> care if hits are returned in doc id order, or any other order. I need only to 
> get maxDocs *best scoring* documents":
> 
> OPTION 1:
> TopDocs top = ixSearcher.search(q, filter, maxDocs);
> 
> OPTION 2:
>    final TopScoreDocCollector tfc = TopScoreDocCollector.create(maxDocs, false);
>     ixSearcher.search(q, filter, tfc);
>     TopDocs top = tfc.topDocs();
> 
> 
> OPTION 3:    
>     final TopFieldCollector tfc = TopFieldCollector.create(Sort.RELEVANCE, 
> maxDocs, 
>         false  /* fillFields */,
>         true   /* trackDocScores */,
>         false   /* trackMaxScore */,
>         false  /* docsInOrder */);
> 
>     ixSearcher.search(q.weight(ixSearcher),filter, tfc);
>     TopDocs top = tfc.topDocs();
> 
> 
> what are the pros and cons?
> If I read javadoc correctly, 
> - OPTION 1 tracks max score and delivers doc Ids in order (suboptimal 
> performance for my case)  
> - OPTION 2 I do not know abut max score tracking, but doc Ids are not required 
> to be in order
> - OPTION 3 looks like exactly what I want, but one performance comment in 
> javadoc about Sort.RELEVANCE made me think if that is the fastest way? 
> 
> What would be recommended here, any other options to achieve the fastest search 
> with above defined conditions (no max score tracking and doc id order 
> irrelevant)?  OPTIN2 looks nice, but as said, I am not sure about max score 
> tracking?
> 
> Thanks,
> eks
> 
> 
> 
> 
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