Class Lucene92HnswVectorsFormat
- java.lang.Object
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- org.apache.lucene.codecs.KnnVectorsFormat
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- org.apache.lucene.backward_codecs.lucene92.Lucene92HnswVectorsFormat
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- All Implemented Interfaces:
NamedSPILoader.NamedSPI
public class Lucene92HnswVectorsFormat extends KnnVectorsFormat
Lucene 9.2 vector format, which encodes numeric vector values and an optional associated graph connecting the documents having values. The graph is used to power HNSW search. The format consists of three files:.vec (vector data) file
For each field:
- Floating-point vector data ordered by field, document ordinal, and vector dimension. The floats are stored in little-endian byte order
- DocIds encoded by
IndexedDISI.writeBitSet(DocIdSetIterator, IndexOutput, byte)
, note that only in sparse case - OrdToDoc was encoded by
DirectMonotonicWriter
, note that only in sparse case
.vex (vector index)
Stores graphs connecting the documents for each field organized as a list of nodes' neighbours as following:
- For each level:
- For each node:
- [int32] the number of neighbor nodes
- array[int32] the neighbor ordinals
- array[int32] padding if the number of the node's neighbors is less than the maximum number of connections allowed on this level. Padding is equal to ((maxConnOnLevel – the number of neighbours) * 4) bytes.
- For each node:
.vem (vector metadata) file
For each field:
- [int32] field number
- [int32] vector similarity function ordinal
- [vlong] offset to this field's vectors in the .vec file
- [vlong] length of this field's vectors, in bytes
- [vlong] offset to this field's index in the .vex file
- [vlong] length of this field's index data, in bytes
- [int] dimension of this field's vectors
- [int] the number of documents having values for this field
- [int8] if equals to -1, dense – all documents have values for a field. If equals to 0, sparse – some documents missing values.
- DocIds were encoded by
IndexedDISI.writeBitSet(DocIdSetIterator, IndexOutput, byte)
- OrdToDoc was encoded by
DirectMonotonicWriter
, note that only in sparse case - [int] the maximum number of connections (neighbours) that each node can have
- [int] number of levels in the graph
- Graph nodes by level. For each level
- [int] the number of nodes on this level
- array[int] for levels greater than 0 list of nodes on this level, stored as the the level 0th nodes ordinals.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Field Summary
Fields Modifier and Type Field Description static int
DEFAULT_BEAM_WIDTH
Default number of the size of the queue maintained while searching during a graph construction.static int
DEFAULT_MAX_CONN
Default number of maximum connections per node-
Fields inherited from class org.apache.lucene.codecs.KnnVectorsFormat
DEFAULT_MAX_DIMENSIONS, EMPTY
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Constructor Summary
Constructors Constructor Description Lucene92HnswVectorsFormat()
A constructor for vectors format with default parametersLucene92HnswVectorsFormat(int maxConn, int beamWidth)
Constructs a format for reading old indexes
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description KnnVectorsReader
fieldsReader(SegmentReadState state)
KnnVectorsWriter
fieldsWriter(SegmentWriteState state)
String
toString()
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Methods inherited from class org.apache.lucene.codecs.KnnVectorsFormat
availableKnnVectorsFormats, forName, getMaxDimensions, getName, reloadKnnVectorsFormat
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Field Detail
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DEFAULT_MAX_CONN
public static final int DEFAULT_MAX_CONN
Default number of maximum connections per node- See Also:
- Constant Field Values
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DEFAULT_BEAM_WIDTH
public static final int DEFAULT_BEAM_WIDTH
Default number of the size of the queue maintained while searching during a graph construction.- See Also:
- Constant Field Values
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Method Detail
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fieldsWriter
public KnnVectorsWriter fieldsWriter(SegmentWriteState state) throws IOException
- Specified by:
fieldsWriter
in classKnnVectorsFormat
- Throws:
IOException
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fieldsReader
public KnnVectorsReader fieldsReader(SegmentReadState state) throws IOException
- Specified by:
fieldsReader
in classKnnVectorsFormat
- Throws:
IOException
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