[Xapian-devel] How the matcher knows when to prune and decay

[Matt Chaput]

>> If the postings are written to disk in document order, and the posting
>> reader object is reading through them linearly, then I would naively assume
>> it can't know what weights are coming up in the list.
> 
> The weighting scheme has a formula for the max weight, derived from the
> formula for the weight.  The chert and brass backends track statistics like
> upper and lower bounds on the document length which make it possible to come
> up with a formula which gives a tighter bound.

Hmm, OK. I can't figure how it would work, but then I'm not a math whiz. Do you know of any papers/chapters/etc. out there that explain this optimization in detail?

Cheers,

Matt