Package org.apache.lucene.codecs.hnsw

Class FlatVectorsReader

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Accountable
    Direct Known Subclasses:
    Lucene99FlatVectorsReader, Lucene99ScalarQuantizedVectorsReader
    public abstract class FlatVectorsReader
extends KnnVectorsReader
    Reads vectors from an index. When searching this reader, it iterates every vector in the index and scores them

    This class is useful when:

    • the number of vectors is small
    • when used along side some additional indexing structure that can be used to better search the vectors (like HNSW).
    WARNING: This API is experimental and might change in incompatible ways in the next release.

    • Field Detail

      • vectorScorer

        protected final FlatVectorsScorer vectorScorer
        Scorer for flat vectors

    • Constructor Detail

      • FlatVectorsReader

        protected FlatVectorsReader​(FlatVectorsScorer vectorsScorer)
        Sole constructor

    • Method Detail

      • search

        public void search​(String field,
                   float[] target,
                   KnnCollector knnCollector,
                   Bits acceptDocs)
            throws IOException
        Description copied from class: KnnVectorsReader
        Return the k nearest neighbor documents as determined by comparison of their vector values for this field, to the given vector, by the field's similarity function. The score of each document is derived from the vector similarity in a way that ensures scores are positive and that a larger score corresponds to a higher ranking.

        The search is allowed to be approximate, meaning the results are not guaranteed to be the true k closest neighbors. For large values of k (for example when k is close to the total number of documents), the search may also retrieve fewer than k documents.

        The returned TopDocs will contain a ScoreDoc for each nearest neighbor, in order of their similarity to the query vector (decreasing scores). The TotalHits contains the number of documents visited during the search. If the search stopped early because it hit visitedLimit, it is indicated through the relation TotalHits.Relation.GREATER_THAN_OR_EQUAL_TO.

        The behavior is undefined if the given field doesn't have KNN vectors enabled on its FieldInfo. The return value is never null.

        Specified by:
        search in class KnnVectorsReader
        Parameters:
        field - the vector field to search
        target - the vector-valued query
        knnCollector - a KnnResults collector and relevant settings for gathering vector results
        acceptDocs - Bits that represents the allowed documents to match, or null if they are all allowed to match.
        Throws:
        IOException

      • search

        public void search​(String field,
                   byte[] target,
                   KnnCollector knnCollector,
                   Bits acceptDocs)
            throws IOException
        Description copied from class: KnnVectorsReader
        Return the k nearest neighbor documents as determined by comparison of their vector values for this field, to the given vector, by the field's similarity function. The score of each document is derived from the vector similarity in a way that ensures scores are positive and that a larger score corresponds to a higher ranking.

        The search is allowed to be approximate, meaning the results are not guaranteed to be the true k closest neighbors. For large values of k (for example when k is close to the total number of documents), the search may also retrieve fewer than k documents.

        The returned TopDocs will contain a ScoreDoc for each nearest neighbor, in order of their similarity to the query vector (decreasing scores). The TotalHits contains the number of documents visited during the search. If the search stopped early because it hit visitedLimit, it is indicated through the relation TotalHits.Relation.GREATER_THAN_OR_EQUAL_TO.

        The behavior is undefined if the given field doesn't have KNN vectors enabled on its FieldInfo. The return value is never null.

        Specified by:
        search in class KnnVectorsReader
        Parameters:
        field - the vector field to search
        target - the vector-valued query
        knnCollector - a KnnResults collector and relevant settings for gathering vector results
        acceptDocs - Bits that represents the allowed documents to match, or null if they are all allowed to match.
        Throws:
        IOException

      • getRandomVectorScorer

        public abstract RandomVectorScorer getRandomVectorScorer​(String field,
                                                         float[] target)
                                                  throws IOException
        Returns a RandomVectorScorer for the given field and target vector.
        Parameters:
        field - the field to search
        target - the target vector
        Returns:
        a RandomVectorScorer for the given field and target vector.
        Throws:
        IOException - if an I/O error occurs when reading from the index.

      • getRandomVectorScorer

        public abstract RandomVectorScorer getRandomVectorScorer​(String field,
                                                         byte[] target)
                                                  throws IOException
        Returns a RandomVectorScorer for the given field and target vector.
        Parameters:
        field - the field to search
        target - the target vector
        Returns:
        a RandomVectorScorer for the given field and target vector.
        Throws:
        IOException - if an I/O error occurs when reading from the index.