[Xapian-tickets] [Xapian] #216: Inconsistent return values for percentage weights

[Xapian]

#216: Inconsistent return values for percentage weights
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 Reporter:  richard  |        Owner:  olly     
     Type:  defect   |       Status:  assigned 
 Priority:  normal   |    Milestone:  1.0.11   
Component:  Matcher  |      Version:  SVN trunk
 Severity:  normal   |   Resolution:           
 Keywords:           |    Blockedby:           
 Platform:  All      |     Blocking:           
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Changes (by olly):

  * milestone:  1.0.10 => 1.0.11


Comment:

 OK, bug216-fix.patch fixes this issue.  However:

  * It means we calculate the weight in potentially many more cases, which
 could be slow
    so we probably also want an API method to say that percentages are
 actually wanted
    as mentioned above.  However, that's not really suitable for 1.0.x -
 we'd have to
    default to calculating percentages so as not to break compatibility
 with existing
    code, and anyone not updating their code to call the new method would
 get penalised.

  * There's an issue where we look at the weight of documents which a
 !MatchDecider
    might reject if offered it.  This means that to be pedantically
 correct, we need to
    pass more documents to any !MatchDecider when sorting (partly) by
 value, which could
    incur quite an overhead.  Currently my patch ignore this with the
 result that the
    percentage weights returned might be lower than they should be in this
 case.

 So the big question of whether we fix this for 1.0.x still remains (the
 patch is
 certainly simple enough to consider).  We do at least now have a patch to
 measure the overhead of if we think it might be worth backporting.

 But I guess we'll probably have to pass on this for 1.0.10 if I want to
 release it this
 weekend though, so bumping the milestone for now at least.

-- 
Ticket URL: <http://trac.xapian.org/ticket/216#comment:14>
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