[Xapian-tickets] [Xapian] #264: Optimise expand using min weight techniques

[Xapian]

#264: Optimise expand using min weight techniques
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 Reporter:  olly         |             Owner:  olly
     Type:  enhancement  |            Status:  assigned
 Priority:  normal       |         Milestone:  1.4.x
Component:  Matcher      |           Version:  git master
 Severity:  minor        |        Resolution:
 Keywords:               |        Blocked By:
 Blocking:               |  Operating System:  All
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Comment (by olly):

 Looking at the expansion code, it looks to me like we fetch the collection
 frequency for every term, which is a waste of effort when we're using the
 default `TradEWeight` weighting - it's only used by `Bo1EWeight`.  We
 should have a `need_stat()` mechanism like `Xapian::Weight` has.

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Ticket URL: <https://trac.xapian.org/ticket/264#comment:6>
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