[Xapian-tickets] [Xapian] #562: QueryParser incorrectly generates stemmed terms for prefixed fields

[Xapian]

#562: QueryParser incorrectly generates stemmed terms for prefixed fields
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 Reporter:  vitalif      |        Owner:  olly    
     Type:  enhancement  |       Status:  reopened
 Priority:  normal       |    Milestone:  1.2.11  
Component:  QueryParser  |      Version:  1.2.6   
 Severity:  minor        |   Resolution:          
 Keywords:               |    Blockedby:          
 Platform:  All          |     Blocking:          
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Changes (by olly):

  * milestone:  => 1.2.11


Old description:

> QueryParser generates stemmed terms for prefixed fields as "PREFIX +
> stem". But TermGenerator indexes them as "Z + PREFIX + stem", so the
> search on stemmed terms inside prefixed fields returns incorrect results.
>
> Example query: "title:идея".
> It generates the following query under STEM_ALL:
> Xapian::Query(Sиде:(pos=1))
> ("иде" is the stem for russian word "идея").
> But, TermGenerator has indexed stemmed term for title as "ZSиде"! So the
> search won't return correct results.

New description:

 !QueryParser generates stemmed terms for prefixed fields as "PREFIX +
 stem". But !TermGenerator indexes them as "Z + PREFIX + stem", so the
 search on stemmed terms inside prefixed fields returns incorrect results.

 Example query: "title:идея".
 It generates the following query under STEM_ALL:
 Xapian::Query(Sиде:(pos=1))
 ("иде" is the stem for russian word "идея").
 But, !TermGenerator has indexed stemmed term for title as "ZSиде"! So the
 search won't return correct results.

--

Comment:

 Half of patch which adds !QueryParser::STEM_ALL_Z applied to trunk in
 r16626, along with test coverage for the new feature.

 Marking to backport to 1.2.11.

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Ticket URL: <http://trac.xapian.org/ticket/562#comment:5>
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