mikemccand commented on code in PR #15979: URL: https://github.com/apache/lucene/pull/15979#discussion_r3682355199
########## lucene/sandbox/src/java/org/apache/lucene/sandbox/codecs/dedup/DedupUtil.java: ########## @@ -0,0 +1,695 @@ +/* + * 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.lucene.sandbox.codecs.dedup; + +import static org.apache.lucene.index.VectorEncoding.BYTE; +import static org.apache.lucene.index.VectorEncoding.FLOAT16; +import static org.apache.lucene.index.VectorEncoding.FLOAT32; +import static org.apache.lucene.search.VectorScorer.Bulk.fromRandomScorerDense; +import static org.apache.lucene.search.VectorScorer.Bulk.fromRandomScorerSparse; +import static org.apache.lucene.util.StringHelper.GOOD_FAST_HASH_SEED; +import static org.apache.lucene.util.StringHelper.murmurhash3_x64_128; + +import java.io.IOException; +import org.apache.lucene.codecs.hnsw.FlatVectorsScorer; +import org.apache.lucene.codecs.lucene95.OffHeapByteVectorValues; +import org.apache.lucene.codecs.lucene95.OffHeapFloat16VectorValues; +import org.apache.lucene.codecs.lucene95.OffHeapFloatVectorValues; +import org.apache.lucene.codecs.lucene95.OrdToDocDISIReaderConfiguration; +import org.apache.lucene.index.ByteVectorValues; +import org.apache.lucene.index.DocsWithFieldSet; +import org.apache.lucene.index.FieldInfo; +import org.apache.lucene.index.Float16VectorValues; +import org.apache.lucene.index.FloatVectorValues; +import org.apache.lucene.index.KnnVectorValues; +import org.apache.lucene.index.VectorEncoding; +import org.apache.lucene.index.VectorSimilarityFunction; +import org.apache.lucene.internal.hppc.IntArrayList; +import org.apache.lucene.search.DocIdSetIterator; +import org.apache.lucene.search.VectorScorer; +import org.apache.lucene.store.IndexInput; +import org.apache.lucene.store.IndexOutput; +import org.apache.lucene.store.RandomAccessInput; +import org.apache.lucene.util.ArrayUtil; +import org.apache.lucene.util.LongValues; +import org.apache.lucene.util.hnsw.RandomVectorScorer; +import org.apache.lucene.util.packed.DirectReader; +import org.apache.lucene.util.packed.DirectWriter; + +/** + * Shared helpers for the de-duplicating flat format: reading / writing field and group metadata, + * vector hashing and alignment, and the {@link DedupVectorValues} views used on the read path. + * + * @lucene.experimental + */ +final class DedupUtil { + + private static final int ORD_TO_DOC_DIRECT_MONOTONIC_BLOCK_SHIFT = 16; + + private static final int END_MARKER = -1; + + private static final int FIELD_ORD_TO_GROUP_ORD_ALIGN_BYTES = 4; + + // TODO: This is the number of bits used to write each group ordinal in the index-backed per-field + // FieldOrdToGroupOrd mapping. Evaluate using fewer bits to reduce index size, at the expense of + // costlier lookups. + private static final int FIELD_ORD_TO_GROUP_ORD_BITS_PER_VALUE = 32; + + /** Initial allocation size for internal re-used int[] scratch buffers. */ + static final int SCRATCH_INITIAL_SIZE = 16; + + /** Key used to group vectors (dimension + encoding). */ + record GroupKey(int dimension, VectorEncoding encoding) { + GroupKey(FieldInfo fieldInfo) { + this(fieldInfo.getVectorDimension(), fieldInfo.getVectorEncoding()); + } + } + + /** + * Vector values that share a single copy of each distinct vector across the documents and fields + * that reference it. + * + * <p>Every instance is backed by two views: the {@code fieldView} maps ordinals to docs and + * drives iteration (one entry per document), while the {@code groupView} holds the de-duplicated + * vectors (one entry per distinct vector). {@code fieldOrdToGroupOrd} translates a document + * ordinal in the field into its group ordinal. + */ + sealed interface DedupVectorValues { + /** The dense view over distinct vectors, indexed by group ordinal. */ + KnnVectorValues getGroupView(); + + /** Maps a per-document ordinal to its group ordinal in {@link #getGroupView()}. */ + FieldOrdToGroupOrd getFieldOrdToGroupOrd(); + } + + /** + * Maps a field's per-document ordinal to the ordinal of its (shared) vector within the group. + * Backed on-heap while writing and off-heap while reading. + */ + sealed interface FieldOrdToGroupOrd { + int get(int ord); + + FieldOrdToGroupOrd copy() throws IOException; + } + + record GroupInfo( + int groupOrd, + int dimension, + VectorEncoding encoding, + int groupSize, + long vectorDataOffset, + long vectorDataSize) {} + + static void writeGroupInfo(IndexOutput meta, GroupInfo groupInfo) throws IOException { + meta.writeInt(groupInfo.groupOrd); + meta.writeInt(groupInfo.dimension); + meta.writeInt(groupInfo.encoding.ordinal()); + meta.writeInt(groupInfo.groupSize); + meta.writeLong(groupInfo.vectorDataOffset); + meta.writeLong(groupInfo.vectorDataSize); + } + + static void writeEndOfGroups(IndexOutput meta) throws IOException { + meta.writeInt(END_MARKER); + } + + static GroupInfo readGroupInfo(IndexInput meta) throws IOException { + int groupOrd = meta.readInt(); + if (groupOrd == END_MARKER) { + return null; + } + + int dimension = meta.readInt(); + VectorEncoding encoding = VectorEncoding.values()[meta.readInt()]; + int groupSize = meta.readInt(); Review Comment: Oh! `groupNumVector`? -- This is an automated message from the Apache Git Service. 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