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

[Xapian]

#400: Optimise AND_MAYBE when the RHS has a maxweight of 0
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 Reporter:  richard      |             Owner:  olly
     Type:  enhancement  |            Status:  new
 Priority:  normal       |         Milestone:  1.3.x
Component:  Matcher      |           Version:  SVN trunk
 Severity:  minor        |        Resolution:
 Keywords:               |        Blocked By:
 Blocking:               |  Operating System:  All
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Comment (by olly):

 It is certainly feasible to check if we're under `OP_SYNONYM`.

 The count of matching subqueries is more problematic though - at present
 we always do count them, and to avoid that we'd need to have the user
 specify up front if they want percentages.

 I guess this is useful for a `PostingSource` which adds weight, and such
 posting sources quite often match all documents - we could perhaps detect
 that and know we could do this optimisation (and just adjust the count
 appropriately).

 This seems quite an esoteric case, and unlikely to be a huge win even
 then, so I don't think it should block 1.4.0.

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Ticket URL: <http://trac.xapian.org/ticket/400#comment:2>
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