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From Chris Hostetter <>
Subject Re: Several questions about scoring/sorting + random sorting in an image/related application
Date Mon, 18 Jun 2007 20:54:27 GMT
: >  for the "recentness" aspect a
: > ValueSourceQuery composed on a ReverseOrdFieldSource should take

: I have a problem with this solution : Document ordering is different
: from Recentness :
: If i upload 1000 images now, they should have the same "recentness",
: even if their order is very different.

ReverseOrdFieldSource isn't based on document ordering, It's based on the
"ordinal value" of the document's value for the specified field ... in
otherwords the reltaive ordering of the documents when sorted by that
field ... the javadocs have an example.

for recentness, this can be advantagous over a specific math calculation
based on the value of "now" because:
  1) the value doesn't fluctuate as now changes -- only as newer documents
are added (the score it produces for the most recent document won't change
just because that document got a day older as long as it's still the most
recent document)
  2) the size of the "gap" between documents doesn't influence the score,
just hte relative order, so documents from last week won't be scoreed
significantly lower then documents from this week just becuase of the
large gap.  (ie: "the last document created on friday night to the first
document published monday morning, as the first document published monday
morning is ot hte second document published monday morning.")

(point #2 is admitedly a subjective benefit, but in practice i think it
helps keep things fair)


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