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From: "Tony Schwartz" <tony@simpleobjects.com>
To: <java-user@lucene.apache.org>
Subject: RE: Implementing paging functionality in lucene
Date: Sun, 24 Jul 2005 12:33:46 -0400
Message-ID: <004901c5906d$7720cb00$0202a8c0@graphite>
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In-Reply-To: <001601c5906b$a5dd95b0$5d1afea9@dsil.danlawinc.com>
Importance: Normal

Don't do that.  Don't use a filter for paging.  Just use the Hits object =
and
get from it only the records applicable for that page.

Tony Schwartz
tony@simpleobjects.com
"We're going to need a lot more cowbell."


-----Original Message-----
From: Harini Raghavan [mailto:harini.raghavan@insideview.com]=20
Sent: Sunday, July 24, 2005 12:21 PM
To: java-user@lucene.apache.org
Subject: Implementing paging functionality in lucene

Hi All,

I am trying to add paging functionality while using lucene search. I =
have
created a PageFilter what takes in the current page num and the number =
of
records as input and invoking the IndexSearcher passing the a Boolean =
Query
object and the PageFilter. The search returns around 1000 records when
invoked without the PageFilter, but with the PageFilter, it returns only =
6
records. I did some debugging and realised that the in the
org.apache.lucene.search.IndexSearcher.search method, the =
bitset.get(doc) is
returning false for all the other documents and so they are not added to =
the
results.
Has someone implemented Paging using filters or tell me if I am missing
something here?

Here is the code :

 public List searchDocuments(DocumentSearchCriteria searchCriteria) =
throws
ApplicationException {
      List results =3D new ArrayList();
      String indexLoc =3D luceneConfig.getIndexDir();
      Directory fsDir =3D getIndexDirectory(indexLoc, false);
      IndexSearcher searcher =3D getIndexSearcher(fsDir);

      Query query =3D indexSearchUtil.getSearchQuery(searchCriteria);
      try {
            Hits hits =3D searcher.search(query, new PageFilter(0,20));
            logger.info("Found " + hits.length() + " document(s) that
matched query '" + query + "':");
            results =3D indexSearchUtil.populateDocumentInfoView(hits,
results);
      } catch(Exception e) {
           logger.error("Exception occurred in searchDocuments()");
      }
      return results;
 }

Here is the PageFilter :

public class PageFilter extends Filter {
    private int start;
    private int end;

    public PageFilter(int pageNum, int pageSize) {
        start =3D pageNum * pageSize;
        end =3D (pageNum+1) * pageSize;
    }

    public BitSet bits(IndexReader reader) throws IOException {
        BitSet result =3D new BitSet(reader.maxDoc());
        for(int i=3Dstart; (i<end) && (i<result.size()); i++) {
            result.set(i);
        }
        return result;
    }
}

Any suggestion would be greatly appreciated.
Thanks,
Harini


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