[Xapian-tickets] [Xapian] #336: valueweightsource1 is failing when assertions are on

[Xapian]

#336: valueweightsource1 is failing when assertions are on
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 Reporter:  richard  |        Owner:  richard  
     Type:  defect   |       Status:  assigned 
 Priority:  normal   |    Milestone:  1.1.0    
Component:  Matcher  |      Version:  SVN trunk
 Severity:  normal   |   Resolution:           
 Keywords:           |    Blockedby:           
 Platform:  All      |     Blocking:           
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Changes (by richard):

  * status:  new => assigned


Comment:

 This turns out to be a long-standing bug in the matcher.  Specifically,
 the situation here is that we have two sub-databases, each with a postlist
 tree consisting of a single posting source.  For the first sub-database,
 the maxweight is 135, for the second it is 100.

 In matcher/mergepostlist.cc, when the first posting source has been
 exhausted, this source is replaced by an EmptyPostList with a maxweight of
 0.  The result of recalc_maxweight() therefore drops to 100, but
 matcher->recalc_maxweight() wasn't being called, resulting in the
 assertion failure.

 This was only happening with multi_chert, because for multi_flint the
 maxweight for both posting sources is DBL_MAX (since the upper bound of
 the values isn't stored).

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Ticket URL: <http://trac.xapian.org/ticket/336#comment:1>
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