[Xapian-tickets] [Xapian] #295: Add support for multi and remote databases with PostingSources (was: Add support for multi databases with PostingSources)

[Xapian]

#295: Add support for multi and remote databases with PostingSources
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 Reporter:  richard      |        Owner:  richard 
     Type:  enhancement  |       Status:  assigned
 Priority:  normal       |    Milestone:  1.1.0   
Component:  Matcher      |      Version:  SVN HEAD
 Severity:  normal       |   Resolution:          
 Keywords:               |    Blockedby:          
 Platform:  All          |     Blocking:          
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Changes (by richard):

  * status:  new => assigned


Comment:

 Will shortly be attaching a patch which adds support for this for remote
 databases, too.

 With this patch, PostingSource requires a clone() method to be implemented
 in all cases, and also requires a name(), serialise() and unserialise()
 method to be implemented for remote matches.  The PostingSource subclass
 needs to be registered with the remote server - ValueWeightPostingSource
 is registered automatically.

 I've also changed the Query constructor which takes a PostingSource to
 take one by reference now, and clone() it.  The Query::Internal object
 then deletes the newly allocated source in its destructor - this is needed
 to make the code in RemoteServer which unserialises the query able to
 supply a newly created source to Query::Internal without having to write
 lots of code to handle the case of such an owned pointer specifically.
 It's also less likely to lead to memory leaks in general, I think, and
 should avoid crashes due to PostingSources created external to Xapian
 going out of scope before get_mset() is called.  (This has been a
 particular problem that I've noticed with the Python bindings - easy
 enough to work around, but a bit startling the first time it happens.)

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Ticket URL: <http://trac.xapian.org/ticket/295#comment:1>
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