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https://issues.apache.org/jira/browse/LUCENE-10382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17479014#comment-17479014
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Michael Sokolov commented on LUCENE-10382:
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How would this look? An easy first step is to add a filter parameter to
KnnVectorQuery
{{ public KnnVectorQuery(String field, float[] target, int k, Bits filter)}}
then it can call {{LeafReader.searchNearestVectors}} with
{{liveDocs.intersect(filter)}} instead of {{liveDocs.}}
[~julietibs] shared on list a link to a paper showing how the search
degenerates for highly selective filters. The writers' approach was to fall
back to "brute force" KNN when selectivity passes a fixed threshold. We could
do that too, and it makes sense to me, but I guess the question is: where
should this fallback happen in the API?
The implementation of full (non-approximate) KNN (with a filter) only needs the
VectorValues iterator which the KnnVectorsReader already provides. It could be
implemented as part of KnnVectorQuery. Is there a better place?
> Allow KnnVectorQuery to operate over a subset of liveDocs
> ---------------------------------------------------------
>
> Key: LUCENE-10382
> URL: https://issues.apache.org/jira/browse/LUCENE-10382
> Project: Lucene - Core
> Issue Type: Improvement
> Affects Versions: 9.0
> Reporter: Joel Bernstein
> Priority: Major
>
> Currently the KnnVectorQuery selects the top K vectors from all live docs.
> This ticket will change the interface to make it possible for the top K
> vectors to be selected from a subset of the live docs.
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