[jira] Commented: (LUCENE-2395) Add a scoring DistanceQuery that does not need caches and separate filters

["Chris Male (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-2395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12857278#action_12857278 ] 

Chris Male commented on LUCENE-2395:
------------------------------------

+1

This will replace the work I was doing on improving the DistanceFilter and the DistanceSortSource.  Instead we will have a proper DistanceQuery where the sorting is done through the existing sorting by score functionality in Lucene.  The CartesianShapeFilter will then be able to be used as a Filter with the new Query.

This also addresses the current problems with caching calculated distances and means that Spatial will work with per segment.

> Add a scoring DistanceQuery that does not need caches and separate filters
> --------------------------------------------------------------------------
>
>                 Key: LUCENE-2395
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2395
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: contrib/spatial
>            Reporter: Uwe Schindler
>             Fix For: 3.1
>
>
> In a chat with Chris Male and my own ideas when implemnting for PANGAEA, I thought about the broken distance query in contrib. It lacks the folloing features:
> - It needs a query for the encldoing bbox (which is constant score)
> - It needs a separate filter for filtering out distances
> - It has no scoring, so if somebody wants to sort by distance, he needs to use the custom sort. For that to work, spatial caches distance calculation (which is borken for multi-segment search)
> The idea is now to combine all three things into one query, but customizeable:
> We first thought about extending CustomScoreQuery and calculate the distance from FieldCache in the customScore method and return a score of 1 for distance=0, score=0 on the max distance and score<0 for farer hits, that are in the bounding box but not in the distance circle. To filter out such negative scores, we would need to override the scorer in CustomScoreQuery which is priate.
> My proposal is now to use a very stripped down CustomScoreQuery (but not extend it) that does call a method getDistance(docId) in its scorer's advance and nextDoc that calculates the distance for the current doc. It stores this distance also in the scorer. If the distance > maxDistance it throws away the hit and calls nextDoc() again. The score() method will reurn per default weight.value*(maxDistance - distance)/maxDistance and uses the precalculated distance. So the distance is only calculated one time in nextDoc()/advance().
> To be able to plug in custom scoring, the following methods in the query can be overridden:
> - float getDistanceScore(double distance) - returns per default: (maxDistance - distance)/maxDistance; allows score customization
> - DocIdSet getBoundingBoxDocIdSet(Reader, LatLng sw, LatLng ne) - returns an DocIdSet for the bounding box. Per default it returns e.g. the docIdSet of a NRF or a cartesian tier filter. You can even plug in any other DocIdSet, e.g. wrap a Query with QueryWrapperFilter
> - support a setter for the GeoDistanceCalculator that is used by the scorer to get the distance.
> This query is almost finished in my head, it just needs coding :-)

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: https://issues.apache.org/jira/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-dev-help@lucene.apache.org