Class KnnVectorQuery
KnnVectorsReader.search(String, float[], KnnCollector, Bits)
to perform nearest
neighbour search.
This query also allows for performing a kNN search subject to a filter. In this case, it first executes the filter for each leaf, then chooses a strategy dynamically:
- If the filter cost is less than k, just execute an exact search
- Otherwise run a kNN search subject to the filter
- If the kNN search visits too many vectors without completing, stop and run an exact search
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Field Summary
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Constructor Summary
ConstructorDescriptionKnnVectorQuery
(String field, float[] target, int k) Deprecated.KnnVectorQuery
(String field, float[] target, int k, Query filter) Deprecated. -
Method Summary
Modifier and TypeMethodDescriptionprotected TopDocs
exactSearch
(LeafReaderContext context, DocIdSetIterator acceptIterator) getField()
int
getK()
protected TopDocs
mergeLeafResults
(TopDocs[] perLeafResults) Merges all segment-level kNN results to get the index-level kNN results.rewrite
(IndexSearcher indexSearcher) Expert: called to re-write queries into primitive queries.void
visit
(QueryVisitor visitor) Recurse through the query tree, visiting any child queries.Methods inherited from class org.apache.lucene.search.KnnFloatVectorQuery
approximateSearch, equals, getTargetCopy, hashCode, toString
Methods inherited from class org.apache.lucene.search.Query
classHash, createWeight, rewrite, sameClassAs, toString
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Field Details
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field
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k
protected final int k
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Constructor Details
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KnnVectorQuery
Deprecated. -
KnnVectorQuery
Deprecated.
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Method Details
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rewrite
Description copied from class:Query
Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.Callers are expected to call
rewrite
multiple times if necessary, until the rewritten query is the same as the original query.The rewrite process may be able to make use of IndexSearcher's executor and be executed in parallel if the executor is provided.
However, if any of the intermediary queries do not satisfy the new API, parallel rewrite is not possible for any subsequent sub-queries. To take advantage of this API, the entire query tree must override this method.
- Overrides:
rewrite
in classQuery
- Throws:
IOException
- See Also:
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exactSearch
protected TopDocs exactSearch(LeafReaderContext context, DocIdSetIterator acceptIterator) throws IOException - Throws:
IOException
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mergeLeafResults
Merges all segment-level kNN results to get the index-level kNN results.The default implementation delegates to
TopDocs.merge(int, TopDocs[])
to find the overall topk
, which requires input results to be sorted.This method is useful for reading and / or modifying the final results as needed.
- Parameters:
perLeafResults
- array of segment-level kNN results.- Returns:
- index-level kNN results (no constraint on their ordering).
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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visit
Description copied from class:Query
Recurse through the query tree, visiting any child queries. -
getField
- Returns:
- the knn vector field where the knn vector search happens.
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getK
public int getK()- Returns:
- the max number of results the KnnVector search returns.
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getFilter
- Returns:
- the filter that is executed before the KnnVector search happens. Only the results accepted by this filter are returned by the KnnVector search.
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KnnFloatVectorQuery
instead