Introduce an int4 off-heap vector scorer (#129824)

* Introduce an int4 off-heap vector scorer

* iter

* Update server/src/main/java/org/elasticsearch/index/codec/vectors/DefaultIVFVectorsReader.java

Co-authored-by: Benjamin Trent <ben.w.trent@gmail.com>

---------

Co-authored-by: Benjamin Trent <ben.w.trent@gmail.com>
This commit is contained in:
Ignacio Vera 2025-06-23 18:44:12 +02:00 committed by GitHub
parent 321a39738a
commit ffea6ca2bf
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11 changed files with 506 additions and 72 deletions

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@ -0,0 +1,123 @@
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the "Elastic License
* 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
* Public License v 1"; you may not use this file except in compliance with, at
* your election, the "Elastic License 2.0", the "GNU Affero General Public
* License v3.0 only", or the "Server Side Public License, v 1".
*/
package org.elasticsearch.benchmark.vector;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.MMapDirectory;
import org.apache.lucene.util.VectorUtil;
import org.elasticsearch.common.logging.LogConfigurator;
import org.elasticsearch.core.IOUtils;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import org.elasticsearch.simdvec.internal.vectorization.ESVectorizationProvider;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.TearDown;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.infra.Blackhole;
import java.io.IOException;
import java.nio.file.Files;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
@State(Scope.Benchmark)
// first iteration is complete garbage, so make sure we really warmup
@Warmup(iterations = 4, time = 1)
// real iterations. not useful to spend tons of time here, better to fork more
@Measurement(iterations = 5, time = 1)
// engage some noise reduction
@Fork(value = 1)
public class Int4ScorerBenchmark {
static {
LogConfigurator.configureESLogging(); // native access requires logging to be initialized
}
@Param({ "384", "702", "1024" })
int dims;
int numVectors = 200;
int numQueries = 10;
byte[] scratch;
byte[][] binaryVectors;
byte[][] binaryQueries;
ES91Int4VectorsScorer scorer;
Directory dir;
IndexInput in;
@Setup
public void setup() throws IOException {
binaryVectors = new byte[numVectors][dims];
dir = new MMapDirectory(Files.createTempDirectory("vectorData"));
try (IndexOutput out = dir.createOutput("vectors", IOContext.DEFAULT)) {
for (byte[] binaryVector : binaryVectors) {
for (int i = 0; i < dims; i++) {
// 4-bit quantization
binaryVector[i] = (byte) ThreadLocalRandom.current().nextInt(16);
}
out.writeBytes(binaryVector, 0, binaryVector.length);
}
}
in = dir.openInput("vectors", IOContext.DEFAULT);
binaryQueries = new byte[numVectors][dims];
for (byte[] binaryVector : binaryVectors) {
for (int i = 0; i < dims; i++) {
// 4-bit quantization
binaryVector[i] = (byte) ThreadLocalRandom.current().nextInt(16);
}
}
scratch = new byte[dims];
scorer = ESVectorizationProvider.getInstance().newES91Int4VectorsScorer(in, dims);
}
@TearDown
public void teardown() throws IOException {
IOUtils.close(dir, in);
}
@Benchmark
@Fork(jvmArgsPrepend = { "--add-modules=jdk.incubator.vector" })
public void scoreFromArray(Blackhole bh) throws IOException {
for (int j = 0; j < numQueries; j++) {
in.seek(0);
for (int i = 0; i < numVectors; i++) {
in.readBytes(scratch, 0, dims);
bh.consume(VectorUtil.int4DotProduct(binaryQueries[j], scratch));
}
}
}
@Benchmark
@Fork(jvmArgsPrepend = { "--add-modules=jdk.incubator.vector" })
public void scoreFromMemorySegmentOnlyVector(Blackhole bh) throws IOException {
for (int j = 0; j < numQueries; j++) {
in.seek(0);
for (int i = 0; i < numVectors; i++) {
bh.consume(scorer.int4DotProduct(binaryQueries[j]));
}
}
}
}

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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the "Elastic License
* 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
* Public License v 1"; you may not use this file except in compliance with, at
* your election, the "Elastic License 2.0", the "GNU Affero General Public
* License v3.0 only", or the "Server Side Public License, v 1".
*/
package org.elasticsearch.simdvec;
import org.apache.lucene.store.IndexInput;
import java.io.IOException;
/** Scorer for quantized vectors stored as an {@link IndexInput}.
* <p>
* Similar to {@link org.apache.lucene.util.VectorUtil#int4DotProduct(byte[], byte[])} but
* one value is read directly from an {@link IndexInput}.
*
* */
public class ES91Int4VectorsScorer {
/** The wrapper {@link IndexInput}. */
protected final IndexInput in;
protected final int dimensions;
protected byte[] scratch;
/** Sole constructor, called by sub-classes. */
public ES91Int4VectorsScorer(IndexInput in, int dimensions) {
this.in = in;
this.dimensions = dimensions;
scratch = new byte[dimensions];
}
public long int4DotProduct(byte[] b) throws IOException {
in.readBytes(scratch, 0, dimensions);
int total = 0;
for (int i = 0; i < dimensions; i++) {
total += scratch[i] * b[i];
}
return total;
}
}

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@ -47,6 +47,10 @@ public class ESVectorUtil {
return ESVectorizationProvider.getInstance().newES91OSQVectorsScorer(input, dimension);
}
public static ES91Int4VectorsScorer getES91Int4VectorsScorer(IndexInput input, int dimension) throws IOException {
return ESVectorizationProvider.getInstance().newES91Int4VectorsScorer(input, dimension);
}
public static long ipByteBinByte(byte[] q, byte[] d) {
if (q.length != d.length * B_QUERY) {
throw new IllegalArgumentException("vector dimensions incompatible: " + q.length + "!= " + B_QUERY + " x " + d.length);

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@ -10,6 +10,7 @@
package org.elasticsearch.simdvec.internal.vectorization;
import org.apache.lucene.store.IndexInput;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import org.elasticsearch.simdvec.ES91OSQVectorsScorer;
import java.io.IOException;
@ -30,4 +31,9 @@ final class DefaultESVectorizationProvider extends ESVectorizationProvider {
public ES91OSQVectorsScorer newES91OSQVectorsScorer(IndexInput input, int dimension) throws IOException {
return new ES91OSQVectorsScorer(input, dimension);
}
@Override
public ES91Int4VectorsScorer newES91Int4VectorsScorer(IndexInput input, int dimension) throws IOException {
return new ES91Int4VectorsScorer(input, dimension);
}
}

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@ -10,6 +10,7 @@
package org.elasticsearch.simdvec.internal.vectorization;
import org.apache.lucene.store.IndexInput;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import org.elasticsearch.simdvec.ES91OSQVectorsScorer;
import java.io.IOException;
@ -31,6 +32,9 @@ public abstract class ESVectorizationProvider {
/** Create a new {@link ES91OSQVectorsScorer} for the given {@link IndexInput}. */
public abstract ES91OSQVectorsScorer newES91OSQVectorsScorer(IndexInput input, int dimension) throws IOException;
/** Create a new {@link ES91Int4VectorsScorer} for the given {@link IndexInput}. */
public abstract ES91Int4VectorsScorer newES91Int4VectorsScorer(IndexInput input, int dimension) throws IOException;
// visible for tests
static ESVectorizationProvider lookup(boolean testMode) {
return new DefaultESVectorizationProvider();

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@ -13,6 +13,7 @@ import org.apache.lucene.store.IndexInput;
import org.apache.lucene.util.Constants;
import org.elasticsearch.logging.LogManager;
import org.elasticsearch.logging.Logger;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import org.elasticsearch.simdvec.ES91OSQVectorsScorer;
import java.io.IOException;
@ -38,6 +39,9 @@ public abstract class ESVectorizationProvider {
/** Create a new {@link ES91OSQVectorsScorer} for the given {@link IndexInput}. */
public abstract ES91OSQVectorsScorer newES91OSQVectorsScorer(IndexInput input, int dimension) throws IOException;
/** Create a new {@link ES91Int4VectorsScorer} for the given {@link IndexInput}. */
public abstract ES91Int4VectorsScorer newES91Int4VectorsScorer(IndexInput input, int dimension) throws IOException;
// visible for tests
static ESVectorizationProvider lookup(boolean testMode) {
final int runtimeVersion = Runtime.version().feature();

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@ -0,0 +1,191 @@
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the "Elastic License
* 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
* Public License v 1"; you may not use this file except in compliance with, at
* your election, the "Elastic License 2.0", the "GNU Affero General Public
* License v3.0 only", or the "Server Side Public License, v 1".
*/
package org.elasticsearch.simdvec.internal.vectorization;
import jdk.incubator.vector.ByteVector;
import jdk.incubator.vector.IntVector;
import jdk.incubator.vector.ShortVector;
import jdk.incubator.vector.Vector;
import jdk.incubator.vector.VectorSpecies;
import org.apache.lucene.store.IndexInput;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import java.io.IOException;
import java.lang.foreign.MemorySegment;
import static java.nio.ByteOrder.LITTLE_ENDIAN;
import static jdk.incubator.vector.VectorOperators.ADD;
import static jdk.incubator.vector.VectorOperators.B2I;
import static jdk.incubator.vector.VectorOperators.B2S;
import static jdk.incubator.vector.VectorOperators.S2I;
/** Panamized scorer for quantized vectors stored as an {@link IndexInput}.
* <p>
* Similar to {@link org.apache.lucene.util.VectorUtil#int4DotProduct(byte[], byte[])} but
* one value is read directly from a {@link MemorySegment}.
* */
public final class MemorySegmentES91Int4VectorsScorer extends ES91Int4VectorsScorer {
private static final VectorSpecies<Byte> BYTE_SPECIES_64 = ByteVector.SPECIES_64;
private static final VectorSpecies<Byte> BYTE_SPECIES_128 = ByteVector.SPECIES_128;
private static final VectorSpecies<Short> SHORT_SPECIES_128 = ShortVector.SPECIES_128;
private static final VectorSpecies<Short> SHORT_SPECIES_256 = ShortVector.SPECIES_256;
private static final VectorSpecies<Integer> INT_SPECIES_128 = IntVector.SPECIES_128;
private static final VectorSpecies<Integer> INT_SPECIES_256 = IntVector.SPECIES_256;
private static final VectorSpecies<Integer> INT_SPECIES_512 = IntVector.SPECIES_512;
private final MemorySegment memorySegment;
public MemorySegmentES91Int4VectorsScorer(IndexInput in, int dimensions, MemorySegment memorySegment) {
super(in, dimensions);
this.memorySegment = memorySegment;
}
@Override
public long int4DotProduct(byte[] q) throws IOException {
if (PanamaESVectorUtilSupport.VECTOR_BITSIZE >= 512 || PanamaESVectorUtilSupport.VECTOR_BITSIZE == 256) {
return dotProduct(q);
}
int i = 0;
int res = 0;
if (dimensions >= 32 && PanamaESVectorUtilSupport.HAS_FAST_INTEGER_VECTORS) {
i += BYTE_SPECIES_128.loopBound(dimensions);
res += int4DotProductBody128(q, i);
}
in.readBytes(scratch, i, dimensions - i);
while (i < dimensions) {
res += scratch[i] * q[i++];
}
return res;
}
private int int4DotProductBody128(byte[] q, int limit) throws IOException {
int sum = 0;
long offset = in.getFilePointer();
for (int i = 0; i < limit; i += 1024) {
ShortVector acc0 = ShortVector.zero(SHORT_SPECIES_128);
ShortVector acc1 = ShortVector.zero(SHORT_SPECIES_128);
int innerLimit = Math.min(limit - i, 1024);
for (int j = 0; j < innerLimit; j += BYTE_SPECIES_128.length()) {
ByteVector va8 = ByteVector.fromArray(BYTE_SPECIES_64, q, i + j);
ByteVector vb8 = ByteVector.fromMemorySegment(BYTE_SPECIES_64, memorySegment, offset + i + j, LITTLE_ENDIAN);
ByteVector prod8 = va8.mul(vb8);
ShortVector prod16 = prod8.convertShape(B2S, ShortVector.SPECIES_128, 0).reinterpretAsShorts();
acc0 = acc0.add(prod16.and((short) 255));
va8 = ByteVector.fromArray(BYTE_SPECIES_64, q, i + j + 8);
vb8 = ByteVector.fromMemorySegment(BYTE_SPECIES_64, memorySegment, offset + i + j + 8, LITTLE_ENDIAN);
prod8 = va8.mul(vb8);
prod16 = prod8.convertShape(B2S, SHORT_SPECIES_128, 0).reinterpretAsShorts();
acc1 = acc1.add(prod16.and((short) 255));
}
IntVector intAcc0 = acc0.convertShape(S2I, INT_SPECIES_128, 0).reinterpretAsInts();
IntVector intAcc1 = acc0.convertShape(S2I, INT_SPECIES_128, 1).reinterpretAsInts();
IntVector intAcc2 = acc1.convertShape(S2I, INT_SPECIES_128, 0).reinterpretAsInts();
IntVector intAcc3 = acc1.convertShape(S2I, INT_SPECIES_128, 1).reinterpretAsInts();
sum += intAcc0.add(intAcc1).add(intAcc2).add(intAcc3).reduceLanes(ADD);
}
in.seek(offset + limit);
return sum;
}
private long dotProduct(byte[] q) throws IOException {
int i = 0;
int res = 0;
// only vectorize if we'll at least enter the loop a single time, and we have at least 128-bit
// vectors (256-bit on intel to dodge performance landmines)
if (dimensions >= 16 && PanamaESVectorUtilSupport.HAS_FAST_INTEGER_VECTORS) {
// compute vectorized dot product consistent with VPDPBUSD instruction
if (PanamaESVectorUtilSupport.VECTOR_BITSIZE >= 512) {
i += BYTE_SPECIES_128.loopBound(dimensions);
res += dotProductBody512(q, i);
} else if (PanamaESVectorUtilSupport.VECTOR_BITSIZE == 256) {
i += BYTE_SPECIES_64.loopBound(dimensions);
res += dotProductBody256(q, i);
} else {
// tricky: we don't have SPECIES_32, so we workaround with "overlapping read"
i += BYTE_SPECIES_64.loopBound(dimensions - BYTE_SPECIES_64.length());
res += dotProductBody128(q, i);
}
}
// scalar tail
for (; i < q.length; i++) {
res += in.readByte() * q[i];
}
return res;
}
/** vectorized dot product body (512 bit vectors) */
private int dotProductBody512(byte[] q, int limit) throws IOException {
IntVector acc = IntVector.zero(INT_SPECIES_512);
long offset = in.getFilePointer();
for (int i = 0; i < limit; i += BYTE_SPECIES_128.length()) {
ByteVector va8 = ByteVector.fromArray(BYTE_SPECIES_128, q, i);
ByteVector vb8 = ByteVector.fromMemorySegment(BYTE_SPECIES_128, memorySegment, offset + i, LITTLE_ENDIAN);
// 16-bit multiply: avoid AVX-512 heavy multiply on zmm
Vector<Short> va16 = va8.convertShape(B2S, SHORT_SPECIES_256, 0);
Vector<Short> vb16 = vb8.convertShape(B2S, SHORT_SPECIES_256, 0);
Vector<Short> prod16 = va16.mul(vb16);
// 32-bit add
Vector<Integer> prod32 = prod16.convertShape(S2I, INT_SPECIES_512, 0);
acc = acc.add(prod32);
}
in.seek(offset + limit); // advance the input stream
// reduce
return acc.reduceLanes(ADD);
}
/** vectorized dot product body (256 bit vectors) */
private int dotProductBody256(byte[] q, int limit) throws IOException {
IntVector acc = IntVector.zero(INT_SPECIES_256);
long offset = in.getFilePointer();
for (int i = 0; i < limit; i += BYTE_SPECIES_64.length()) {
ByteVector va8 = ByteVector.fromArray(BYTE_SPECIES_64, q, i);
ByteVector vb8 = ByteVector.fromMemorySegment(BYTE_SPECIES_64, memorySegment, offset + i, LITTLE_ENDIAN);
// 32-bit multiply and add into accumulator
Vector<Integer> va32 = va8.convertShape(B2I, INT_SPECIES_256, 0);
Vector<Integer> vb32 = vb8.convertShape(B2I, INT_SPECIES_256, 0);
acc = acc.add(va32.mul(vb32));
}
in.seek(offset + limit);
// reduce
return acc.reduceLanes(ADD);
}
/** vectorized dot product body (128 bit vectors) */
private int dotProductBody128(byte[] q, int limit) throws IOException {
IntVector acc = IntVector.zero(INT_SPECIES_128);
long offset = in.getFilePointer();
// 4 bytes at a time (re-loading half the vector each time!)
for (int i = 0; i < limit; i += BYTE_SPECIES_64.length() >> 1) {
// load 8 bytes
ByteVector va8 = ByteVector.fromArray(BYTE_SPECIES_64, q, i);
ByteVector vb8 = ByteVector.fromMemorySegment(BYTE_SPECIES_64, memorySegment, offset + i, LITTLE_ENDIAN);
// process first "half" only: 16-bit multiply
Vector<Short> va16 = va8.convert(B2S, 0);
Vector<Short> vb16 = vb8.convert(B2S, 0);
Vector<Short> prod16 = va16.mul(vb16);
// 32-bit add
acc = acc.add(prod16.convertShape(S2I, INT_SPECIES_128, 0));
}
in.seek(offset + limit);
// reduce
return acc.reduceLanes(ADD);
}
}

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@ -11,6 +11,7 @@ package org.elasticsearch.simdvec.internal.vectorization;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.MemorySegmentAccessInput;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import org.elasticsearch.simdvec.ES91OSQVectorsScorer;
import java.io.IOException;
@ -39,4 +40,15 @@ final class PanamaESVectorizationProvider extends ESVectorizationProvider {
}
return new ES91OSQVectorsScorer(input, dimension);
}
@Override
public ES91Int4VectorsScorer newES91Int4VectorsScorer(IndexInput input, int dimension) throws IOException {
if (PanamaESVectorUtilSupport.HAS_FAST_INTEGER_VECTORS && input instanceof MemorySegmentAccessInput msai) {
MemorySegment ms = msai.segmentSliceOrNull(0, input.length());
if (ms != null) {
return new MemorySegmentES91Int4VectorsScorer(input, dimension, ms);
}
}
return new ES91Int4VectorsScorer(input, dimension);
}
}

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@ -0,0 +1,60 @@
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the "Elastic License
* 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
* Public License v 1"; you may not use this file except in compliance with, at
* your election, the "Elastic License 2.0", the "GNU Affero General Public
* License v3.0 only", or the "Server Side Public License, v 1".
*/
package org.elasticsearch.simdvec.internal.vectorization;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.MMapDirectory;
import org.apache.lucene.util.VectorUtil;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
public class ES91Int4VectorScorerTests extends BaseVectorizationTests {
public void testInt4DotProduct() throws Exception {
// only even dimensions are supported
final int dimensions = random().nextInt(1, 1000) * 2;
final int numVectors = random().nextInt(1, 100);
final byte[] vector = new byte[dimensions];
try (Directory dir = new MMapDirectory(createTempDir())) {
try (IndexOutput out = dir.createOutput("tests.bin", IOContext.DEFAULT)) {
for (int i = 0; i < numVectors; i++) {
for (int j = 0; j < dimensions; j++) {
vector[j] = (byte) random().nextInt(16); // 4-bit quantization
}
out.writeBytes(vector, 0, dimensions);
}
}
final byte[] query = new byte[dimensions];
for (int j = 0; j < dimensions; j++) {
query[j] = (byte) random().nextInt(16); // 4-bit quantization
}
try (IndexInput in = dir.openInput("tests.bin", IOContext.DEFAULT)) {
// Work on a slice that has just the right number of bytes to make the test fail with an
// index-out-of-bounds in case the implementation reads more than the allowed number of
// padding bytes.
final IndexInput slice = in.slice("test", 0, (long) dimensions * numVectors);
final IndexInput slice2 = in.slice("test2", 0, (long) dimensions * numVectors);
final ES91Int4VectorsScorer defaultScorer = defaultProvider().newES91Int4VectorsScorer(slice, dimensions);
final ES91Int4VectorsScorer panamaScorer = maybePanamaProvider().newES91Int4VectorsScorer(slice2, dimensions);
for (int i = 0; i < numVectors; i++) {
in.readBytes(vector, 0, dimensions);
long val = VectorUtil.int4DotProduct(vector, query);
assertEquals(val, defaultScorer.int4DotProduct(query));
assertEquals(val, panamaScorer.int4DotProduct(query));
assertEquals(in.getFilePointer(), slice.getFilePointer());
assertEquals(in.getFilePointer(), slice2.getFilePointer());
}
assertEquals((long) dimensions * numVectors, in.getFilePointer());
}
}
}
}

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@ -19,6 +19,7 @@ import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.VectorUtil;
import org.apache.lucene.util.hnsw.NeighborQueue;
import org.elasticsearch.index.codec.vectors.reflect.OffHeapStats;
import org.elasticsearch.simdvec.ES91Int4VectorsScorer;
import org.elasticsearch.simdvec.ES91OSQVectorsScorer;
import org.elasticsearch.simdvec.ESVectorUtil;
@ -48,25 +49,23 @@ public class DefaultIVFVectorsReader extends IVFVectorsReader implements OffHeap
@Override
CentroidQueryScorer getCentroidScorer(FieldInfo fieldInfo, int numCentroids, IndexInput centroids, float[] targetQuery)
throws IOException {
FieldEntry fieldEntry = fields.get(fieldInfo.number);
float[] globalCentroid = fieldEntry.globalCentroid();
float globalCentroidDp = fieldEntry.globalCentroidDp();
OptimizedScalarQuantizer scalarQuantizer = new OptimizedScalarQuantizer(fieldInfo.getVectorSimilarityFunction());
byte[] quantized = new byte[targetQuery.length];
float[] targetScratch = ArrayUtil.copyArray(targetQuery);
OptimizedScalarQuantizer.QuantizationResult queryParams = scalarQuantizer.scalarQuantize(
targetScratch,
final FieldEntry fieldEntry = fields.get(fieldInfo.number);
final float globalCentroidDp = fieldEntry.globalCentroidDp();
final OptimizedScalarQuantizer scalarQuantizer = new OptimizedScalarQuantizer(fieldInfo.getVectorSimilarityFunction());
final byte[] quantized = new byte[targetQuery.length];
final OptimizedScalarQuantizer.QuantizationResult queryParams = scalarQuantizer.scalarQuantize(
ArrayUtil.copyArray(targetQuery),
quantized,
(byte) 4,
globalCentroid
fieldEntry.globalCentroid()
);
final ES91Int4VectorsScorer scorer = ESVectorUtil.getES91Int4VectorsScorer(centroids, fieldInfo.getVectorDimension());
return new CentroidQueryScorer() {
int currentCentroid = -1;
private final byte[] quantizedCentroid = new byte[fieldInfo.getVectorDimension()];
private final float[] centroid = new float[fieldInfo.getVectorDimension()];
private final float[] centroidCorrectiveValues = new float[3];
private int quantizedCentroidComponentSum;
private final long centroidByteSize = fieldInfo.getVectorDimension() + 3 * Float.BYTES + Short.BYTES;
private final long rawCentroidsOffset = (long) numCentroids * (fieldInfo.getVectorDimension() + 3 * Float.BYTES + Short.BYTES);
private final long rawCentroidsByteSize = (long) Float.BYTES * fieldInfo.getVectorDimension();
@Override
public int size() {
@ -75,35 +74,67 @@ public class DefaultIVFVectorsReader extends IVFVectorsReader implements OffHeap
@Override
public float[] centroid(int centroidOrdinal) throws IOException {
readQuantizedAndRawCentroid(centroidOrdinal);
if (centroidOrdinal != currentCentroid) {
centroids.seek(rawCentroidsOffset + rawCentroidsByteSize * centroidOrdinal);
centroids.readFloats(centroid, 0, centroid.length);
currentCentroid = centroidOrdinal;
}
return centroid;
}
private void readQuantizedAndRawCentroid(int centroidOrdinal) throws IOException {
if (centroidOrdinal == currentCentroid) {
return;
public void bulkScore(NeighborQueue queue) throws IOException {
// TODO: bulk score centroids like we do with posting lists
centroids.seek(0L);
for (int i = 0; i < numCentroids; i++) {
queue.add(i, score());
}
centroids.seek(centroidOrdinal * centroidByteSize);
quantizedCentroidComponentSum = readQuantizedValue(centroids, quantizedCentroid, centroidCorrectiveValues);
centroids.seek(numCentroids * centroidByteSize + (long) Float.BYTES * quantizedCentroid.length * centroidOrdinal);
centroids.readFloats(centroid, 0, centroid.length);
currentCentroid = centroidOrdinal;
}
@Override
public float score(int centroidOrdinal) throws IOException {
readQuantizedAndRawCentroid(centroidOrdinal);
private float score() throws IOException {
final float qcDist = scorer.int4DotProduct(quantized);
centroids.readFloats(centroidCorrectiveValues, 0, 3);
final int quantizedCentroidComponentSum = Short.toUnsignedInt(centroids.readShort());
return int4QuantizedScore(
quantized,
qcDist,
queryParams,
fieldInfo.getVectorDimension(),
quantizedCentroid,
centroidCorrectiveValues,
quantizedCentroidComponentSum,
globalCentroidDp,
fieldInfo.getVectorSimilarityFunction()
);
}
// TODO can we do this in off-heap blocks?
private float int4QuantizedScore(
float qcDist,
OptimizedScalarQuantizer.QuantizationResult queryCorrections,
int dims,
float[] targetCorrections,
int targetComponentSum,
float centroidDp,
VectorSimilarityFunction similarityFunction
) {
float ax = targetCorrections[0];
// Here we assume `lx` is simply bit vectors, so the scaling isn't necessary
float lx = (targetCorrections[1] - ax) * FOUR_BIT_SCALE;
float ay = queryCorrections.lowerInterval();
float ly = (queryCorrections.upperInterval() - ay) * FOUR_BIT_SCALE;
float y1 = queryCorrections.quantizedComponentSum();
float score = ax * ay * dims + ay * lx * (float) targetComponentSum + ax * ly * y1 + lx * ly * qcDist;
if (similarityFunction == EUCLIDEAN) {
score = queryCorrections.additionalCorrection() + targetCorrections[2] - 2 * score;
return Math.max(1 / (1f + score), 0);
} else {
// For cosine and max inner product, we need to apply the additional correction, which is
// assumed to be the non-centered dot-product between the vector and the centroid
score += queryCorrections.additionalCorrection() + targetCorrections[2] - centroidDp;
if (similarityFunction == MAXIMUM_INNER_PRODUCT) {
return VectorUtil.scaleMaxInnerProductScore(score);
}
return Math.max((1f + score) / 2f, 0);
}
}
};
}
@ -111,10 +142,7 @@ public class DefaultIVFVectorsReader extends IVFVectorsReader implements OffHeap
NeighborQueue scorePostingLists(FieldInfo fieldInfo, KnnCollector knnCollector, CentroidQueryScorer centroidQueryScorer, int nProbe)
throws IOException {
NeighborQueue neighborQueue = new NeighborQueue(centroidQueryScorer.size(), true);
// TODO Off heap scoring for quantized centroids?
for (int centroid = 0; centroid < centroidQueryScorer.size(); centroid++) {
neighborQueue.add(centroid, centroidQueryScorer.score(centroid));
}
centroidQueryScorer.bulkScore(neighborQueue);
return neighborQueue;
}
@ -125,39 +153,6 @@ public class DefaultIVFVectorsReader extends IVFVectorsReader implements OffHeap
return new MemorySegmentPostingsVisitor(target, indexInput.clone(), entry, fieldInfo, needsScoring);
}
// TODO can we do this in off-heap blocks?
static float int4QuantizedScore(
byte[] quantizedQuery,
OptimizedScalarQuantizer.QuantizationResult queryCorrections,
int dims,
byte[] binaryCode,
float[] targetCorrections,
int targetComponentSum,
float centroidDp,
VectorSimilarityFunction similarityFunction
) {
float qcDist = VectorUtil.int4DotProduct(quantizedQuery, binaryCode);
float ax = targetCorrections[0];
// Here we assume `lx` is simply bit vectors, so the scaling isn't necessary
float lx = (targetCorrections[1] - ax) * FOUR_BIT_SCALE;
float ay = queryCorrections.lowerInterval();
float ly = (queryCorrections.upperInterval() - ay) * FOUR_BIT_SCALE;
float y1 = queryCorrections.quantizedComponentSum();
float score = ax * ay * dims + ay * lx * (float) targetComponentSum + ax * ly * y1 + lx * ly * qcDist;
if (similarityFunction == EUCLIDEAN) {
score = queryCorrections.additionalCorrection() + targetCorrections[2] - 2 * score;
return Math.max(1 / (1f + score), 0);
} else {
// For cosine and max inner product, we need to apply the additional correction, which is
// assumed to be the non-centered dot-product between the vector and the centroid
score += queryCorrections.additionalCorrection() + targetCorrections[2] - centroidDp;
if (similarityFunction == MAXIMUM_INNER_PRODUCT) {
return VectorUtil.scaleMaxInnerProductScore(score);
}
return Math.max((1f + score) / 2f, 0);
}
}
@Override
public Map<String, Long> getOffHeapByteSize(FieldInfo fieldInfo) {
return Map.of();
@ -356,12 +351,4 @@ public class DefaultIVFVectorsReader extends IVFVectorsReader implements OffHeap
}
}
static int readQuantizedValue(IndexInput indexInput, byte[] binaryValue, float[] corrections) throws IOException {
assert corrections.length == 3;
indexInput.readBytes(binaryValue, 0, binaryValue.length);
corrections[0] = Float.intBitsToFloat(indexInput.readInt());
corrections[1] = Float.intBitsToFloat(indexInput.readInt());
corrections[2] = Float.intBitsToFloat(indexInput.readInt());
return Short.toUnsignedInt(indexInput.readShort());
}
}

View file

@ -332,7 +332,7 @@ public abstract class IVFVectorsReader extends KnnVectorsReader {
float[] centroid(int centroidOrdinal) throws IOException;
float score(int centroidOrdinal) throws IOException;
void bulkScore(NeighborQueue queue) throws IOException;
}
interface PostingVisitor {