Package org.apache.lucene.search

Class KnnFloatVectorQuery

java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.search.KnnFloatVectorQuery
Direct Known Subclasses:
KnnVectorQuery
public class KnnFloatVectorQuery extends Query
Uses 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

  • Field Details

    • field

      protected final String field

    • k

      protected final int k

  • Constructor Details

    • KnnFloatVectorQuery

      public KnnFloatVectorQuery(String field, float[] target, int k)
      Find the k nearest documents to the target vector according to the vectors in the given field. target vector.
      Parameters:
      field - a field that has been indexed as a KnnFloatVectorField.
      target - the target of the search
      k - the number of documents to find
      Throws:
      IllegalArgumentException - if k is less than 1

    • KnnFloatVectorQuery

      public KnnFloatVectorQuery(String field, float[] target, int k, Query filter)
      Find the k nearest documents to the target vector according to the vectors in the given field. target vector.
      Parameters:
      field - a field that has been indexed as a KnnFloatVectorField.
      target - the target of the search
      k - the number of documents to find
      filter - a filter applied before the vector search
      Throws:
      IllegalArgumentException - if k is less than 1

  • Method Details

    • approximateSearch

      protected TopDocs approximateSearch(LeafReaderContext context, Bits acceptDocs, int visitedLimit) throws IOException
      Throws:
      IOException

    • toString

      public String toString(String field)
      Description copied from class: Query
      Prints a query to a string, with field assumed to be the default field and omitted.
      Specified by:
      toString in class Query

    • equals

      public boolean equals(Object o)
      Description copied from class: Query
      Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly.

      Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical to those of the other instance. Utility methods are provided for certain repetitive code.

      See Also:

    • hashCode

      public int hashCode()
      Description copied from class: Query
      Override and implement query hash code properly in a subclass. This is required so that QueryCache works properly.
      See Also:

    • getTargetCopy

      public float[] getTargetCopy()
      Returns:
      the target query vector of the search. Each vector element is a float.

    • rewrite

      public Query rewrite(IndexSearcher indexSearcher) throws IOException
      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 class Query
      Throws:
      IOException
      See Also:

    • exactSearch

      protected TopDocs exactSearch(LeafReaderContext context, DocIdSetIterator acceptIterator) throws IOException
      Throws:
      IOException

    • mergeLeafResults

      protected TopDocs mergeLeafResults(TopDocs[] perLeafResults)
      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 top k, 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.

    • visit

      public void visit(QueryVisitor visitor)
      Description copied from class: Query
      Recurse through the query tree, visiting any child queries.
      Specified by:
      visit in class Query
      Parameters:
      visitor - a QueryVisitor to be called by each query in the tree

    • getField

      public String getField()
      Returns:
      the knn vector field where the knn vector search happens.

    • getK

      public int getK()
      Returns:
      the max number of results the KnnVector search returns.

    • getFilter

      public Query 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.