[Xapian-tickets] [Xapian] #400: Optimise AND_MAYBE when the RHS has a maxweight of 0

Xapian nobody at xapian.org
Wed Sep 9 14:44:31 BST 2009


#400: Optimise AND_MAYBE when the RHS has a maxweight of 0
-------------------------+--------------------------------------------------
 Reporter:  richard      |       Owner:  olly     
     Type:  enhancement  |      Status:  new      
 Priority:  normal       |   Milestone:  1.2.0    
Component:  Matcher      |     Version:  SVN trunk
 Severity:  minor        |   Blockedby:           
 Platform:  All          |    Blocking:           
-------------------------+--------------------------------------------------
 If the RHS of an AND_MAYBE clause has an RHS whose maxweight is 0 (or
 becomes zero during the search), the AND_MAYBE could be replaced with the
 LHS.  The attached patch does this.  However, it doesn't quite work, due
 to two side effects:

  - if the AND_MAYBE is part of an OP_SYNONYM, the wdf of the RHS of the
 AND_MAYBE can have an effect, but will be lost.

  - if a percentage weight calculation is in effect, the count of the
 number of terms matching will miss those in the AND_MAYBE.

 This doesn't change API at all, so doesn't need to be fixed during the 1.1
 series.

-- 
Ticket URL: <http://trac.xapian.org/ticket/400>
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