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From Apache Wiki <wikidi...@apache.org>
Subject [Solr Wiki] Update of "FunctionQuery" by YonikSeeley
Date Fri, 23 Oct 2009 01:27:16 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Solr Wiki" for change notification.

The "FunctionQuery" page has been changed by YonikSeeley.
The comment on this change is: point to relevancy faq for more date boosting.
http://wiki.apache.org/solr/FunctionQuery?action=diff&rev1=28&rev2=29

--------------------------------------------------

  
    Example: '''ms(datefield1,datefield2)'''
  
- 
+ === Date Boosting ===
  Boosting more recent content is a common use case.  One way is to use a {{{recip}}} function
in conjunction with {{{ms}}}.
  
  There are approximately 3.16e10 milliseconds in a year, so one can scale dates to fractions
of a year with the inverse, or 3.16e-11.  Thus the function '''recip(ms(NOW,mydatefield),3.16e-11,1,1)'''
will yield values near 1 for very recent documents, 1/2 for documents a year old, 1/3 for
documents two years old, etc.  Be careful to not use this function for dates more than one
year in the future or the values will be negative.
  
  The most effective way to use such a boost is to multiply it with the relevancy score, rather
than add it in.  One way to do this is with the [[http://lucene.apache.org/solr/api/org/apache/solr/search/BoostQParserPlugin.html|boost]]
query parser.
+ 
+ Also see http://wiki.apache.org/solr/SolrRelevancyFAQ#How_can_I_boost_the_score_of_newer_documents
  
  == top ==
  <!> [[Solr1.4]]

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