SOLR-17780: Add support for scalar quantized dense vectors #3385
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| /* | ||
| * Licensed to the Apache Software Foundation (ASF) under one or more | ||
| * contributor license agreements. See the NOTICE file distributed with | ||
| * this work for additional information regarding copyright ownership. | ||
| * The ASF licenses this file to You under the Apache License, Version 2.0 | ||
| * (the "License"); you may not use this file except in compliance with | ||
| * the License. You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package org.apache.solr.schema; | ||
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| import org.apache.lucene.codecs.KnnVectorsFormat; | ||
| import org.apache.lucene.codecs.lucene99.Lucene99HnswScalarQuantizedVectorsFormat; | ||
| import org.apache.lucene.codecs.lucene99.Lucene99ScalarQuantizedVectorsFormat; | ||
| import org.apache.lucene.index.VectorEncoding; | ||
| import org.apache.lucene.index.VectorSimilarityFunction; | ||
| import org.apache.solr.common.SolrException; | ||
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| import java.util.Map; | ||
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| import static java.util.Optional.ofNullable; | ||
| import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsFormat.DEFAULT_NUM_MERGE_WORKER; | ||
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| public class ScalarQuantizedDenseVectorField extends DenseVectorField { | ||
| public static final String BITS = "bits"; // | ||
| public static final String CONFIDENCE_INTERVAL = "confidenceInterval"; | ||
| public static final String DYNAMIC_CONFIDENCE_INTERVAL = "dynamicConfidenceInterval"; | ||
| public static final String COMPRESS = "compress"; // can only be enabled when bits = 4 per Lucene codec spec | ||
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There was a problem hiding this comment. these first four lines are param names if I'm not mistaken. Maybe we can call them '_PARAM' e.g. 'BITS_PARAM' Or add a comment line at the beginning that clearly group them as param names, There was a problem hiding this comment. to be fair, checking the original DenseVectorField, the same renaming could help there as well I suspect |
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| private static final int DEFAULT_BITS = 7; // use signed byte as default when unspecified | ||
| private static final Float DEFAULT_CONFIDENCE_INTERVAL = null; // use dimension scaled confidence interval | ||
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| /** | ||
| * Number of bits to use for storage | ||
| * Must be 4 (half-byte) or 7 (signed-byte) per Lucene codec spec | ||
| */ | ||
| private int bits; | ||
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| /** | ||
| * Confidence interval to use for scalar quantization | ||
| * Default is calculated as `1-1/(vector_dimensions + 1)` | ||
| */ | ||
| private Float confidenceInterval; | ||
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| /** | ||
| * When enabled, in conjunction with 4 bit size, will pair values into single bytes for 50% reduction in memory usage | ||
| * (comes at the cost of some decode speed penalty) | ||
| */ | ||
| private boolean compress; | ||
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| public ScalarQuantizedDenseVectorField(int dimension, | ||
| VectorSimilarityFunction similarityFunction, | ||
| VectorEncoding vectorEncoding, | ||
| int bits, | ||
| Float confidenceInterval, | ||
| boolean compress) { | ||
| super(dimension, similarityFunction, vectorEncoding); | ||
| this.bits = bits; | ||
| this.confidenceInterval = confidenceInterval; | ||
| this.compress = compress; | ||
| } | ||
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| @Override | ||
| public void init(IndexSchema schema, Map<String, String> args) { | ||
| super.init(schema, args); | ||
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| this.bits = ofNullable(args.remove(BITS)) | ||
| .map(Integer::parseInt) | ||
| .orElse(DEFAULT_BITS); | ||
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| this.compress = ofNullable(args.remove(COMPRESS)) | ||
| .map(Boolean::parseBoolean) | ||
| .orElse(false); | ||
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| this.confidenceInterval = ofNullable(args.remove(CONFIDENCE_INTERVAL)) | ||
| .map(Float::parseFloat) | ||
| .orElse(DEFAULT_CONFIDENCE_INTERVAL); | ||
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| if (ofNullable(args.remove(DYNAMIC_CONFIDENCE_INTERVAL)) | ||
| .map(Boolean::parseBoolean) | ||
| .orElse(false)) { | ||
| this.confidenceInterval = Lucene99ScalarQuantizedVectorsFormat.DYNAMIC_CONFIDENCE_INTERVAL; | ||
| } | ||
| } | ||
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| @Override | ||
| public KnnVectorsFormat buildKnnVectorsFormat() { | ||
| final String knnAlgorithm = getKnnAlgorithm(); | ||
| if (KNN_ALGORITHM.equals(knnAlgorithm)) { | ||
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There was a problem hiding this comment. mmmm not sure about this part: The only knn algorithm supported right now is 'HNSW'. The vector storage format is directly (and only) used by a the graph format parent ( I had in my to-do list to re-organise the package to easily differentiate graph from storage formats) Lucene99HnswVectorsFormat uses Lucene99FlatVectorsFormat. Lucene99HnswScalarQuantizedVectorsFormat uses Lucene99ScalarQuantizedVectorsFormat (for scalar quantisation). Given that, I suspect with this contribution we want to differentiate between: -> the if then else should be changed I suspect, I don't understand it as it is right now as we are mixing a graph format (Lucene99HnswScalarQuantizedVectorsFormat already using the scalar quantised storage format) and a vectore storage format (Lucene99ScalarQuantizedVectorsFormat) There was a problem hiding this comment. From an initial review the ScalarQuantizedDenseVectorField should always return the Lucene99HnswScalarQuantizedVectorsFormat. The traditional DenseVectorField, should always return Lucene99HnswVectorsFormat |
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| return new Lucene99HnswScalarQuantizedVectorsFormat( | ||
| getHnswMaxConn(), | ||
| getHnswBeamWidth(), | ||
| DEFAULT_NUM_MERGE_WORKER, | ||
| getBits(), | ||
| useCompression(), | ||
| getConfidenceInterval(), | ||
| null | ||
| ); | ||
| } else if (FLAT_ALGORITHM.equals(knnAlgorithm)) { | ||
| return new Lucene99ScalarQuantizedVectorsFormat( | ||
| getConfidenceInterval(), | ||
| getBits(), | ||
| useCompression()); | ||
| } else { | ||
| throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, String.format("Unrecognized KNN algorithm: %s", knnAlgorithm)); | ||
| } | ||
| } | ||
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| public int getBits() { | ||
| return bits; | ||
| } | ||
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| public boolean useCompression() { | ||
| return compress; | ||
| } | ||
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| public Float getConfidenceInterval() { | ||
| return confidenceInterval; | ||
| } | ||
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| } | ||
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'VECTOR_STORAGE_ALGORITHM' maybe?
Is it used somewhere?
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reading it more we are mixing up the 'knn' algorithm (only HNSW supported right now), with the 'vector storage' (flat, scalarQuantised and binaryQuantised