[Xapian-tickets] [Xapian] #484: QueryParser does not expand wildcarded terms in some cases

[Xapian]

#484: QueryParser does not expand wildcarded terms in some cases
---------------------------+------------------------------------------------
 Reporter:  Daniel.Menard  |       Owner:  olly
     Type:  defect         |      Status:  new 
 Priority:  normal         |   Milestone:      
Component:  QueryParser    |     Version:      
 Severity:  normal         |    Keywords:      
Blockedby:                 |    Platform:  All 
 Blocking:                 |  
---------------------------+------------------------------------------------
 Hi,

 It seems that the query parser does not expand wildcards if the query
 contains at least 3 terms and the wildcarded term is in the middle of the
 query.

 Exemples:

 {{{
 OK : test* xapian user -> testable OR tester OR xapian OR user.
 OK : xapian user test* -> xapian OR user OR testable OR tester.
 NOT OK : xapian test* user -> xapian OR test OR user.
 }}}

 Attached is a small PHP script which reproduce the problem.

 On my machine (Windows XP, Xapian php-bindings 1.2.0 binaries from
 flax.co.uk, php 5.2.13), this script produces the following output:

 {{{
 PHP version 5.2.13, Xapian version 1.2.0

 Creating a new db containing one document with terms : xapian, tester,
 testable, user, query,

 query:  test* xapian
 result: Xapian::Query(((testable:(pos=1) SYNONYM tester:(pos=1)) OR
 xapian:(pos=2)))
 OK.

 query:  xapian test*
 result: Xapian::Query((xapian:(pos=1) OR (testable:(pos=2) SYNONYM
 tester:(pos=2))))
 OK.

 query:  test* xapian user
 result: Xapian::Query(((testable:(pos=1) SYNONYM tester:(pos=1)) OR
 xapian:(pos=2) OR user:(pos=3)))
 OK.

 query:  xapian user test*
 result: Xapian::Query((xapian:(pos=1) OR user:(pos=2) OR (testable:(pos=3)
 SYNONYM tester:(pos=3))))
 OK.

 query:  xapian test* user
 result: Xapian::Query((xapian:(pos=1) OR test:(pos=2) OR user:(pos=3)))
 expect: Xapian::Query((xapian:(pos=1) OR (testable:(pos=2) SYNONYM
 tester:(pos=2)) OR user:(pos=3)))
 FAILS.

 query:  xapian query test* user
 result: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR test:(pos=3) OR
 user:(pos=4)))
 expect: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR
 (testable:(pos=3) SYNONYM tester:(pos=3)) OR user:(pos=4)))
 FAILS.

 query:  xapian que* test* user
 result: Xapian::Query((xapian:(pos=1) OR que:(pos=2) OR test:(pos=3) OR
 user:(pos=4)))
 expect: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR
 (testable:(pos=3) SYNONYM tester:(pos=3)) OR user:(pos=4)))
 FAILS.

 query:  xapian que* user test*
 result: Xapian::Query((xapian:(pos=1) OR que:(pos=2) OR user:(pos=3) OR
 test:(pos=4)))
 expect: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR user:(pos=3) OR
 (testable:(pos=4) SYNONYM tester:(pos=4))))
 FAILS.
 }}}

 I tried with various older versions of Xapian and I think that the problem
 was introduced in Xapian 1.0.2 because my tests pass with Xapian 1.0.1 but
 not with more recent versions:

 {{{
 PHP version 5.2.13, Xapian version 1.0.1

 Creating a new db containing one document with terms : xapian, tester,
 testable, user, query,

 query:  test* xapian
 result: Xapian::Query((testable:(pos=1) OR tester:(pos=1) OR
 xapian:(pos=2)))
 OK.

 query:  xapian test*
 result: Xapian::Query((xapian:(pos=1) OR testable:(pos=2) OR
 tester:(pos=2)))
 OK.

 query:  test* xapian user
 result: Xapian::Query((testable:(pos=1) OR tester:(pos=1) OR
 xapian:(pos=2) OR user:(pos=3)))
 OK.

 query:  xapian user test*
 result: Xapian::Query((xapian:(pos=1) OR user:(pos=2) OR testable:(pos=3)
 OR tester:(pos=3)))
 OK.

 query:  xapian test* user
 result: Xapian::Query((xapian:(pos=1) OR testable:(pos=2) OR
 tester:(pos=2) OR user:(pos=3)))
 OK.

 query:  xapian query test* user
 result: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR testable:(pos=3)
 OR tester:(pos=3) OR user:(pos=4)))
 OK.

 query:  xapian que* test* user
 result: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR testable:(pos=3)
 OR tester:(pos=3) OR user:(pos=4)))
 OK.

 query:  xapian que* user test*
 result: Xapian::Query((xapian:(pos=1) OR query:(pos=2) OR user:(pos=3) OR
 testable:(pos=4) OR tester:(pos=4)))
 OK.
 }}}

 Sorry for spotting only now a 3 years old problem!

-- 
Ticket URL: <http://trac.xapian.org/ticket/484>
Xapian <http://xapian.org/>
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