Package org.apache.lucene.util.hnsw

Class HnswGraphSearcher

java.lang.Object

org.apache.lucene.util.hnsw.HnswGraphSearcher

public class HnswGraphSearcher
extends Object

Searches an HNSW graph to find nearest neighbors to a query vector. For more background on the search algorithm, see HnswGraph.

Constructor Summary

Constructors

Constructor	Description
HnswGraphSearcher(NeighborQueue candidates, BitSet visited)	Creates a new graph searcher.

Method Summary

Modifier and Type	Method	Description
static KnnCollector	search(RandomVectorScorer scorer, int topK, OnHeapHnswGraph graph, Bits acceptOrds, int visitedLimit)	Search OnHeapHnswGraph, this method is thread safe.
static void	search(RandomVectorScorer scorer, KnnCollector knnCollector, HnswGraph graph, Bits acceptOrds)	Searches HNSW graph for the nearest neighbors of a query vector.
HnswGraphBuilder.GraphBuilderKnnCollector	searchLevel(RandomVectorScorer scorer, int topK, int level, int[] eps, HnswGraph graph)	Searches for the nearest neighbors of a query vector in a given level.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

HnswGraphSearcher

public HnswGraphSearcher(NeighborQueue candidates,
 BitSet visited)

Creates a new graph searcher.

Parameters:

candidates - max heap that will track the candidate nodes to explore

visited - bit set that will track nodes that have already been visited

Method Details

search

public static void search(RandomVectorScorer scorer,
 KnnCollector knnCollector,
 HnswGraph graph,
 Bits acceptOrds)
                   throws IOException

Searches HNSW graph for the nearest neighbors of a query vector.

Parameters:

scorer - the scorer to compare the query with the nodes

knnCollector - a collector of top knn results to be returned

graph - the graph values. May represent the entire graph, or a level in a hierarchical graph.

acceptOrds - Bits that represents the allowed document ordinals to match, or null if they are all allowed to match.

Throws:

IOException

search

public static KnnCollector search(RandomVectorScorer scorer,
 int topK,
 OnHeapHnswGraph graph,
 Bits acceptOrds,
 int visitedLimit)
                           throws IOException

Search OnHeapHnswGraph, this method is thread safe.

Parameters:

scorer - the scorer to compare the query with the nodes

topK - the number of nodes to be returned

graph - the graph values. May represent the entire graph, or a level in a hierarchical graph.

acceptOrds - Bits that represents the allowed document ordinals to match, or null if they are all allowed to match.

visitedLimit - the maximum number of nodes that the search is allowed to visit

Returns:

a set of collected vectors holding the nearest neighbors found

Throws:

IOException

searchLevel

public HnswGraphBuilder.GraphBuilderKnnCollector searchLevel(RandomVectorScorer scorer,
 int topK,
 int level,
 int[] eps,
 HnswGraph graph)
                                                      throws IOException

Searches for the nearest neighbors of a query vector in a given level.

If the search stops early because it reaches the visited nodes limit, then the results will be marked incomplete through NeighborQueue.incomplete().

Parameters:

scorer - the scorer to compare the query with the nodes

topK - the number of nearest to query results to return

level - level to search

eps - the entry points for search at this level expressed as level 0th ordinals

graph - the graph values

Returns:

a set of collected vectors holding the nearest neighbors found

Throws:

IOException