[Xapian-tickets] [Xapian] #378: Optimise MultiAndPostList using current weight of lhs

[Xapian]

#378: Optimise MultiAndPostList using current weight of lhs
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 Reporter:  richard      |       Owner:  richard  
     Type:  enhancement  |      Status:  assigned 
 Priority:  normal       |   Milestone:  1.1.2    
Component:  Matcher      |     Version:  SVN trunk
 Severity:  normal       |    Keywords:           
Blockedby:               |    Platform:  All      
 Blocking:               |  
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Comment(by olly):

 I think major overhauls of the matcher are out of scope for 1.1.x at this
 point - we don't want to risk destabilising changes, and if anything we're
 approaching time to start being brutal and culling some things which
 currently have milestones set for 1.1.x.

 I don't think speculatively executing in parallel is a sane approach for
 most users, and there's a significant risk that the rival searches would
 compete for I/O and cache resources
 resulting in a slower result overall anyway.

 Thinking more about this, I feel nervous about making this change with no
 idea of how bad it could make things, so I think it would be useful to try
 to quantify what slowdown we might see in the worst case.

 Do you still have the large database you were testing this on?  If so, it
 would be good to try one or both of the likely "bad cases" above.  I can
 probably even try to implement the required postingsources if you don't
 have the time, but I don't think I have a suitable database around to test
 with.

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Ticket URL: <http://trac.xapian.org/ticket/378#comment:6>
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