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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: SpanQuery and BoostingTermQuery oddities
Date Wed, 12 Aug 2009 10:25:19 GMT
All Span*Query seem to rely on the SpanQuery.createWeight (which
returns SpanWeight/SpanScorer) to make their weight/scorer.
SpanScorer in turn simply enumerates all spans summing up their
"sloppy freq" and always scoring with that, regardless of the sub
queries.

So SpanNearQuery (or any composite span query, eg even SpanFirstQuery
I think will do this), disregards the scores of its child query/ies.

I agree it's odd... it seems like composite span queries ought to take
their child query scoring into account.  This would be a benefit of
merging into the normal Query*, since these composite queries already
factor in scoring from their sub queries.

Mike

On Wed, Aug 5, 2009 at 11:01 AM, Mark Miller<markrmiller@gmail.com> wrote:
> Grant Ingersoll wrote:
>>
>> On Aug 5, 2009, at 10:07 AM, Mark Miller wrote:
>>>
>>> Yeah - SpanQuery's don't use the boosts from subspans - it just uses the
>>> idf for the query terms and the span length I believe - and the boost for
>>> the top level Query.
>>>
>>> Is that the right way to go? I guess Doug seemed to think so? I don't
>>> know. It is sort of a bug that lower boosts would be ignored right? There is
>>> an issue for it somewhere.
>>>
>>> It gets complicated quick to change it - all of a sudden you need
>>> something like BooleanQuery ...
>>>
>>
>> Not sure it needs BooleanQuery, but it does seem like it should take into
>> account the scores of the subclauses (regardless of BoostingTermQuery).
>>  There is a spot in creating the SpanScorer where it gets the value from the
>> QueryWeight, but this QueryWeight does not account for the subclauses
>> QueryWeights.
>>
>
> It doesn't need BooleanQuery - it needs BooleanQuery type logic - which is
> fairly complicated. At least to do it right I think. I don't have a clear
> memory of it, but I started to try and address this once and ...
> well I didn't continue.
>
> --
> - Mark
>
> http://www.lucidimagination.com
>
>
>
>
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