Using a function in a filter query

[Pete Smith <pe...@lovefilm.com>]

I want to filter my result set before I search. I know the correct way
to do this is by using the filter query (fq) parameter. However, I want
to filter based on the output of a function performed on a field.

I have a field 'rating' which is an integer in the range of 1 to ~75000.
The upper limit may change. I want to filter to the top 500 items with
the highest 'rating'. In SQL this would be something like:

... ORDER BY rating DESC LIMIT 500

I think I can get the documents in solr ranked by rating descending by
using the function rord(rating), so basically I would like to do:

fq=rord(rating):[0 TO 500]

But that does not seem possible. Does anyone know what else I could do?



-- 
Pete Smith
Senior Developer

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Re: Using a function in a filter query

[Yonik Seeley <yo...@lucidimagination.com>]

On Mon, Apr 20, 2009 at 12:40 PM, Pete Smith <pe...@lovefilm.com> wrote:
> fq=rord(rating):[0 TO 500]

Solr 1.4 can now do range queries on arbitrary functions:
http://lucene.apache.org/solr/api/org/apache/solr/search/FunctionRangeQParserPlugin.html

Note that ord() and rord() won't work properly in Solr 1.4 trunk.
Lucene has changed to searching per-segment in a MultiReader and hence
you will currently get the ord() or rord() in that segment, not in the
whole index.

-Yonik
http://www.lucidimagination.com