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From Apache Wiki <wikidi...@apache.org>
Subject [Lucene-java Wiki] Update of "ImproveSearchingSpeed" by KarlWettin
Date Wed, 16 Jul 2008 12:56:43 GMT
Dear Wiki user,

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

The following page has been changed by KarlWettin:
http://wiki.apache.org/lucene-java/ImproveSearchingSpeed

The comment on the change is:
Filters

------------------------------------------------------------------------------
  
   Fuzzy queries perform CPU-intensive string comparisons - avoid comparing all unique terms
with the user input by only examining terms starting with the first "N" characters. This prefix
length is a property on both QueryParser and FuzzyQuery - default is zero so ALL terms are
compared. 
  
+  * '''Consider using [http://hudson.zones.apache.org/hudson/job/Lucene-trunk/javadoc/org/apache/lucene/search/Filter.html
filters].'''
+ 
+  It can be much more efficient to restrict results to a part of the index using a cached
bit set filter rather than using a query clause. This is especially true for restrictions
that match a great number of documents of a large index. Filters are typically used to restrict
the results to a category but could in many cases be used to replace any query clause. One
difference between using a Query and a Filter is that the Query has an impact on the score
while a Filter does not.
+ 

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