It's Field.TOKENIZED in pre-2.4 Lucene.

Mike

mitu2009 wrote:


Am using Lucene.Net 2.0.4 version and am not able to see
"Field.Index.ANALYZED" in the code.

Thanks,
Ed


Steven A Rowe wrote:

Hi Ed,

Here's an example, based on the code from
<http://wiki.apache.org/lucene-java/TheBasics> (UNTESTED):

public class LuceneFreshnessTest {
 public static void main(String[] args) throws IOException {
   RAMDirectory directory = new RAMDirectory();
   IndexWriter writer =
     new IndexWriter(directory, new WhitespaceAnalyzer(), true);
   Document doc = new Document();
   doc.add(new Field("id", "1", Field.Store.YES,
                     Field.Index.NOT_ANALYZED));
   // 1 day since epoch = "1"
   Field daysField = new Field
     ("days", "1", Field.Store.NO, Field.Index.ANALYZED);
   daysField.setOmitNorms(true);
   doc.add(daysField);
   writer.addDocument(doc);

   doc = new Document();
   doc.add(new Field("id", "2", Field.Store.YES,
                     Field.Index.NOT_ANALYZED));
   // 3 days since epoch = "1 1 1"
   daysField = new Field("days", "1 1 1", Field.Store.NO,
                         Field.Index.ANALYZED);
   daysField.setOmitNorms(true);
   doc.add(daysField);
   writer.addDocument(doc);

   doc = new Document();
   doc.add(new Field("id", "3", Field.Store.YES,
                     Field.Index.NOT_ANALYZED));
   // 5 days since epoch = "1 1 1 1 1"
   daysField = new Field("days", "1 1 1 1 1", Field.Store.NO,
                         Field.Index.ANALYZED);
   daysField.setOmitNorms(true);
   doc.add(daysField);
   writer.addDocument(doc);

   writer.close();

   IndexSearcher searcher = new IndexSearcher(directory);
   Query query = new TermQuery(new Term("days", "1"));
   TopDocs rs = searcher.search(query, null, 10);
   System.out.println("Total hits: " + rs.totalHits);

   Document firstHit = searcher.doc(rs.scoreDocs[0].doc);
   System.out.println("First hit ID (newest=3): "
                      + firstHit.getField("id").toString());
 }
}

Steve

On 01/15/2009 at 10:41 PM, mitu2009 wrote:
Hi,

Thanks for your suggestions!
Am new to Lucene...would appreciate if u could elaborate ur
following point with an example:

Add a separate field, say "days", in which you will put as many "1" as many days elapsed since the epoch (not neccessarily since 1 Jan 1970 - pick a date that makes sense for you). Then, if you want to prioritize newer documents, just add "+days:1" to your query. Voila - the final results are a sum of other score factors plus a score factor that is
higher for more recent document, containing more 1-s.

Thanks again!
Ed

Steven A Rowe wrote:

On 01/14/2009 at 10:44 PM, mitu2009 wrote:
Is it possible to bubble up newer records in lucene search results? ie.I want Lucene to give a higher score to records which are closer
to
today's date.

In addition to the fine ideas given by previous posters, Andrzej
Bialecki has described a technique that uses term frequency alone to
affect the score: from
<http://www.gossamer-threads.com/lists/lucene/java-user/43457>:

Here's the trick that works for me, without the issues of boost
resolution or FunctionQuery.

Add a separate field, say "days", in which you will put as many "1"
as
many days elapsed since the epoch (not neccessarily since 1 Jan 1970
-
pick a date that makes sense for you). Then, if you want to
prioritize
newer documents, just add "+days:1" to your query. Voila - the final results are a sum of other score factors plus a score factor that is
higher for more recent document, containing more 1-s.

If you are dealing with large time spans, you can split this into
years and days-in-a-year, and apply query boosts, like "+years: 1^10.0
+days:1^0.02". Do some experiments and find what works
best for you.

As noted in a later thread discussing this issue
<http://www.gossamer-threads.com/lists/lucene/java-user/64482>, you
should turn norms off on the "days" field:

<http://lucene.apache.org/java/2_4_0/api/org/apache/lucene/document/Fieldable.html#setOmitNorms(boolean) >

Steve

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