Re: custom sorting

[Doug Daniels <dd...@rooftophq.com>]

If you went with the FunctionQuery approach for sorting by distance, would
there be any way to use the output of the FunctionQuery to limit the
documents to those within a certain radius?  Or is it just for boosting
documents, not for filtering?

Also, even if you're just using it for boosting, is there a way to avoid
running the expensive function on all docs in the index?  Could you somehow
nest bounding-box RangeQuery for latitude and longitude inside as
ValueSources?

Thanks,
Doug


hossman wrote:
> 
> 
> : leaks, etc.).  (Speaking of which, could anyone with more Lucene/Solr
> : experience than I comment on the performance characteristics of the
> : locallucene implementation mentioned on the list recently?  I've taken
> : a first look and it seems reasonable to me.)
> 
> i cna't speak for anyone else, but i haven't had a chacne to drill into it 
> yet.
> 
> : Using a function query, as Yonik suggests above, is another approach.
> : But to get a true sort, you have to boost the original query to zero?
> 
> or a very close approximation there of (0.000001 perhaps)
> 
> keep in mind: a "true" distance sort while easy to explain may not be as 
> useful as a sort by score where the distance is factored into the score 
> ... there have been some threads about this on the java-user list in the 
> past and it's been discussed that a really relevant result 2 miles away is 
> probably better then a mildly relevent result 1.5 miles away ... that's 
> where a function query with well choosen boosts might serve you better.
> 
> : How does this impact the results returned by the original query?  Will
> : the requirements (and boosts) of the original (now nested) query
> : remain intact, only sorted by the function?  Also, is there any way to
> 
> it should ... but i won't swear to that.
> 
> : do this with the dismax handler?
> 
> a strict sort on the value of a a function?  put the function in the bf
> param, don't bother with bq or pf params and change your qf params to all 
> have really small boosts.
> 
> 
> 
> -Hoss
> 
> 
> 

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Re: custom sorting

[Chris Hostetter <ho...@fucit.org>]

: If you went with the FunctionQuery approach for sorting by distance, would
: there be any way to use the output of the FunctionQuery to limit the
: documents to those within a certain radius?  Or is it just for boosting
: documents, not for filtering?

FunctionQueries don't restrict the set of documents at all, so you would 
need to combine it with a seperate query that limits the documents ... the 
simplest way would be as you say: by combining it with two range queries 
that would define a lat/lon "bounding box"

: Also, even if you're just using it for boosting, is there a way to avoid
: running the expensive function on all docs in the index?  Could you somehow

that's the bueaty of "skipTo" in query scoring ... BooleanQueries keep 
track of the "next" document each clause can match (in order by docid), 
and tell all of the other queries to "skipTo" that doc and not bother 
trying to score any doc ids below that.



-Hoss