[Xapian-tickets] [Xapian] #406: When defaultOp is AND, QueryParser produces <matchNothing> for requests containing a wildcard term and at least two stopwords

[Xapian]

#406: When defaultOp is AND, QueryParser produces <matchNothing> for requests
containing a wildcard term and at least two stopwords
---------------------------+------------------------------------------------
 Reporter:  Daniel.Menard  |       Owner:  olly  
     Type:  defect         |      Status:  new   
 Priority:  normal         |   Milestone:        
Component:  QueryParser    |     Version:  1.0.16
 Severity:  normal         |    Keywords:        
Blockedby:                 |    Platform:  All   
 Blocking:                 |  
---------------------------+------------------------------------------------
 One of my users reported that our search engine was not always removing
 stopwords from the user query.

 By investigating, I found that the query parser was returning a
 <matchNothing> Query for requests containing a wildcard and at least two
 stopwords, but only when defaultOp is AND (everyhing is fine if defaultOp
 is OR).

 Attached is a small PHP script which reproduce the problem.

 On my machine (Windows XP, Xapian php-bindings 1.0.16 binaries from
 flax.co.uk, php 5.2.9-2), this script produces the following output:

 {{{
 C:\php>php b:\test.php
 PHP version 5.2.9-2, Xapian version 1.0.16

 Creating a new db containing a document with terms : test, tester,
 testable, user,

 -------------- DefaultOp=OR--------------
 query: this is a test
 result: Xapian::Query(test:(pos=4))

 query: test*
 result: Xapian::Query((test:(pos=1) OR testable:(pos=1) OR
 tester:(pos=1)))

 query: a test*
 result: Xapian::Query((test:(pos=2) OR testable:(pos=2) OR
 tester:(pos=2)))

 query: is a test*
 result: Xapian::Query((test:(pos=3) OR testable:(pos=3) OR
 tester:(pos=3)))

 query: this is a test*
 result: Xapian::Query((test:(pos=4) OR testable:(pos=4) OR
 tester:(pos=4)))

 query: this is a us* test*
 result: Xapian::Query((user:(pos=4) OR test:(pos=5) OR testable:(pos=5) OR
 tester:(pos=5)))

 query: this is a user test*
 result: Xapian::Query((user:(pos=4) OR test:(pos=5) OR testable:(pos=5) OR
 tester:(pos=5)))

 -------------- DefaultOp=AND--------------
 query: this is a test
 result: Xapian::Query(test:(pos=4))

 query: test*
 result: Xapian::Query((test:(pos=1) OR testable:(pos=1) OR
 tester:(pos=1)))

 query: a test*
 result: Xapian::Query((test:(pos=2) OR testable:(pos=2) OR
 tester:(pos=2)))

 query: is a test*
 result: Xapian::Query()
 FAILS.

 query: this is a test*
 result: Xapian::Query()
 FAILS.

 query: this is a us* test*
 result: Xapian::Query()
 FAILS.

 query: this is a user test*
 result: Xapian::Query((user:(pos=4) AND (test:(pos=5) OR testable:(pos=5)
 OR tester:(pos=5))))
 }}}

 The problem is very specific: the query must contain a wildcard term, at
 least two stop words (1 wildcard + 1 stopword works well!) and no other
 term.

 Also, the problem is not new: I've tested with xapian 1.0.11 and 1.0.12
 which produce the same output.

-- 
Ticket URL: <http://trac.xapian.org/ticket/406>
Xapian <http://xapian.org/>
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