[Xapian-tickets] [Xapian] #608: as_partial_query / as_wildcarded_query and limiting the expansion of terms

Xapian nobody at xapian.org
Wed Nov 28 17:25:34 GMT 2012


#608: as_partial_query / as_wildcarded_query and limiting the expansion of terms
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 Reporter:  boomboo      |       Owner:  olly    
     Type:  enhancement  |      Status:  assigned
 Priority:  normal       |   Milestone:  1.3.2   
Component:  QueryParser  |     Version:          
 Severity:  normal       |    Keywords:          
Blockedby:               |    Platform:  All     
 Blocking:               |  
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Comment(by boomboo):

 As far as the magic number (100) goes, we did a test to find out what
 would the number need to be to hit whatever the user typed.

 We used our database and actual user queries as the test cases, the
 numbers for us were that 100 terms gives us 84% hit ratio given two
 letters and 98% for 3 letters, changing the number of terms to 40 for 3
 letters gave us 95% coverage. In general the number of terms needed rises
 exponentially from around 80%. For comparison the previous numbers were
 1340 terms for 84% (2l) and 600 for 98% (3l) without sorting.

 The test though is only valid for our test case and usage pattern,
 however, the number of letters in the partial term should probably be
 taken into account when using a default or changing
 max_wildcard_expansion.

-- 
Ticket URL: <http://trac.xapian.org/ticket/608#comment:4>
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