LUCENE-9905: rename VectorValues.SearchStrategy to VectorValues.SimilarityFunction

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene60/Lucene60FieldInfosFormat.java

@@ -212,7 +212,7 @@ public final class Lucene60FieldInfosFormat extends FieldInfosFormat {
                 pointIndexDimensionCount,
                 pointNumBytes,
                 0,
-                VectorValues.SearchStrategy.NONE,
+                VectorValues.SimilarityFunction.NONE,
                 isSoftDeletesField);
       } catch (IllegalStateException e) {
         throw new CorruptIndexException(

lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextFieldInfosFormat.java

@@ -158,7 +158,7 @@ public class SimpleTextFieldInfosFormat extends FieldInfosFormat {
         SimpleTextUtil.readLine(input, scratch);
         assert StringHelper.startsWith(scratch.get(), VECTOR_SEARCH_STRATEGY);
         String scoreFunction = readString(VECTOR_SEARCH_STRATEGY.length, scratch);
-        VectorValues.SearchStrategy vectorDistFunc = distanceFunction(scoreFunction);
+        VectorValues.SimilarityFunction vectorDistFunc = distanceFunction(scoreFunction);
 
         SimpleTextUtil.readLine(input, scratch);
         assert StringHelper.startsWith(scratch.get(), SOFT_DELETES);
@@ -201,8 +201,8 @@ public class SimpleTextFieldInfosFormat extends FieldInfosFormat {
     return DocValuesType.valueOf(dvType);
   }
 
-  public VectorValues.SearchStrategy distanceFunction(String scoreFunction) {
-    return VectorValues.SearchStrategy.valueOf(scoreFunction);
+  public VectorValues.SimilarityFunction distanceFunction(String scoreFunction) {
+    return VectorValues.SimilarityFunction.valueOf(scoreFunction);
   }
 
   private String readString(int offset, BytesRefBuilder scratch) {
@@ -298,7 +298,7 @@ public class SimpleTextFieldInfosFormat extends FieldInfosFormat {
         SimpleTextUtil.writeNewline(out);
 
         SimpleTextUtil.write(out, VECTOR_SEARCH_STRATEGY);
-        SimpleTextUtil.write(out, fi.getVectorSearchStrategy().name(), scratch);
+        SimpleTextUtil.write(out, fi.getVectorSimilarityFunction().name(), scratch);
         SimpleTextUtil.writeNewline(out);
 
         SimpleTextUtil.write(out, SOFT_DELETES);

lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextVectorReader.java

@@ -82,8 +82,8 @@ public class SimpleTextVectorReader extends VectorReader {
       while (fieldNumber != -1) {
         String fieldName = readString(in, FIELD_NAME);
         String scoreFunctionName = readString(in, SCORE_FUNCTION);
-        VectorValues.SearchStrategy searchStrategy =
-            VectorValues.SearchStrategy.valueOf(scoreFunctionName);
+        VectorValues.SimilarityFunction similarityFunction =
+            VectorValues.SimilarityFunction.valueOf(scoreFunctionName);
         long vectorDataOffset = readLong(in, VECTOR_DATA_OFFSET);
         long vectorDataLength = readLong(in, VECTOR_DATA_LENGTH);
         int dimension = readInt(in, VECTOR_DIMENSION);
@@ -95,7 +95,8 @@ public class SimpleTextVectorReader extends VectorReader {
         assert fieldEntries.containsKey(fieldName) == false;
         fieldEntries.put(
             fieldName,
-            new FieldEntry(dimension, searchStrategy, vectorDataOffset, vectorDataLength, docIds));
+            new FieldEntry(
+                dimension, similarityFunction, vectorDataOffset, vectorDataLength, docIds));
         fieldNumber = readInt(in, FIELD_NUMBER);
       }
       SimpleTextUtil.checkFooter(in);
@@ -204,7 +205,7 @@ public class SimpleTextVectorReader extends VectorReader {
   private static class FieldEntry {
 
     final int dimension;
-    final VectorValues.SearchStrategy searchStrategy;
+    final VectorValues.SimilarityFunction similarityFunction;
 
     final long vectorDataOffset;
     final long vectorDataLength;
@@ -212,12 +213,12 @@ public class SimpleTextVectorReader extends VectorReader {
 
     FieldEntry(
         int dimension,
-        VectorValues.SearchStrategy searchStrategy,
+        VectorValues.SimilarityFunction similarityFunction,
         long vectorDataOffset,
         long vectorDataLength,
         int[] ordToDoc) {
       this.dimension = dimension;
-      this.searchStrategy = searchStrategy;
+      this.similarityFunction = similarityFunction;
       this.vectorDataOffset = vectorDataOffset;
       this.vectorDataLength = vectorDataLength;
       this.ordToDoc = ordToDoc;
@@ -260,8 +261,8 @@ public class SimpleTextVectorReader extends VectorReader {
     }
 
     @Override
-    public SearchStrategy searchStrategy() {
-      return entry.searchStrategy;
+    public SimilarityFunction similarityFunction() {
+      return entry.similarityFunction;
     }
 
     @Override

lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextVectorWriter.java

@@ -98,7 +98,7 @@ public class SimpleTextVectorWriter extends VectorWriter {
       throws IOException {
     writeField(meta, FIELD_NUMBER, field.number);
     writeField(meta, FIELD_NAME, field.name);
-    writeField(meta, SCORE_FUNCTION, field.getVectorSearchStrategy().name());
+    writeField(meta, SCORE_FUNCTION, field.getVectorSimilarityFunction().name());
     writeField(meta, VECTOR_DATA_OFFSET, vectorDataOffset);
     writeField(meta, VECTOR_DATA_LENGTH, vectorDataLength);
     writeField(meta, VECTOR_DIMENSION, field.getVectorDimension());

lucene/codecs/src/test/org/apache/lucene/codecs/uniformsplit/TestBlockWriter.java

@@ -116,7 +116,7 @@ public class TestBlockWriter extends LuceneTestCase {
         0,
         0,
         0,
-        VectorValues.SearchStrategy.NONE,
+        VectorValues.SimilarityFunction.NONE,
         true);
   }
 }

lucene/codecs/src/test/org/apache/lucene/codecs/uniformsplit/sharedterms/TestSTBlockReader.java

@@ -203,7 +203,7 @@ public class TestSTBlockReader extends LuceneTestCase {
         0,
         0,
         0,
-        VectorValues.SearchStrategy.NONE,
+        VectorValues.SimilarityFunction.NONE,
         false);
   }
 

lucene/core/src/java/org/apache/lucene/codecs/VectorWriter.java

@@ -68,18 +68,18 @@ public abstract class VectorWriter implements Closeable {
     }
     List<VectorValuesSub> subs = new ArrayList<>();
     int dimension = -1;
-    VectorValues.SearchStrategy searchStrategy = null;
+    VectorValues.SimilarityFunction similarityFunction = null;
     int nonEmptySegmentIndex = 0;
     for (int i = 0; i < mergeState.vectorReaders.length; i++) {
       VectorReader vectorReader = mergeState.vectorReaders[i];
       if (vectorReader != null) {
         if (mergeFieldInfo != null && mergeFieldInfo.hasVectorValues()) {
           int segmentDimension = mergeFieldInfo.getVectorDimension();
-          VectorValues.SearchStrategy segmentSearchStrategy =
-              mergeFieldInfo.getVectorSearchStrategy();
+          VectorValues.SimilarityFunction segmentSimilarityFunction =
+              mergeFieldInfo.getVectorSimilarityFunction();
           if (dimension == -1) {
             dimension = segmentDimension;
-            searchStrategy = mergeFieldInfo.getVectorSearchStrategy();
+            similarityFunction = mergeFieldInfo.getVectorSimilarityFunction();
           } else if (dimension != segmentDimension) {
             throw new IllegalStateException(
                 "Varying dimensions for vector-valued field "
@@ -88,14 +88,14 @@ public abstract class VectorWriter implements Closeable {
                     + dimension
                     + "!="
                     + segmentDimension);
-          } else if (searchStrategy != segmentSearchStrategy) {
+          } else if (similarityFunction != segmentSimilarityFunction) {
             throw new IllegalStateException(
-                "Varying search strategys for vector-valued field "
+                "Varying similarity functions for vector-valued field "
                     + mergeFieldInfo.name
                     + ": "
-                    + searchStrategy
+                    + similarityFunction
                     + "!="
-                    + segmentSearchStrategy);
+                    + segmentSimilarityFunction);
           }
           VectorValues values = vectorReader.getVectorValues(mergeFieldInfo.name);
           if (values != null) {
@@ -241,8 +241,8 @@ public abstract class VectorWriter implements Closeable {
     }
 
     @Override
-    public SearchStrategy searchStrategy() {
-      return subs.get(0).values.searchStrategy();
+    public SimilarityFunction similarityFunction() {
+      return subs.get(0).values.similarityFunction();
     }
 
     class MergerRandomAccess implements RandomAccessVectorValues {
@@ -272,8 +272,8 @@ public abstract class VectorWriter implements Closeable {
       }
 
       @Override
-      public SearchStrategy searchStrategy() {
-        return VectorValuesMerger.this.searchStrategy();
+      public SimilarityFunction similarityFunction() {
+        return VectorValuesMerger.this.similarityFunction();
       }
 
       @Override

lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90FieldInfosFormat.java

@@ -29,8 +29,7 @@ import org.apache.lucene.index.FieldInfos;
 import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.IndexOptions;
 import org.apache.lucene.index.SegmentInfo;
-import org.apache.lucene.index.VectorValues;
-import org.apache.lucene.index.VectorValues.SearchStrategy;
+import org.apache.lucene.index.VectorValues.SimilarityFunction;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.DataOutput;
 import org.apache.lucene.store.Directory;
@@ -103,8 +102,8 @@ import org.apache.lucene.store.IndexOutput;
  *   <li>VectorDistFunction: a byte containing distance function used for similarity calculation.
  *       <ul>
  *         <li>0: no distance function is defined for this field.
- *         <li>1: EUCLIDEAN_HNSW distance. ({@link SearchStrategy#EUCLIDEAN_HNSW})
- *         <li>2: DOT_PRODUCT_HNSW score. ({@link SearchStrategy#DOT_PRODUCT_HNSW})
+ *         <li>1: EUCLIDEAN_HNSW distance. ({@link SimilarityFunction#EUCLIDEAN})
+ *         <li>2: DOT_PRODUCT_HNSW score. ({@link SimilarityFunction#DOT_PRODUCT})
  *       </ul>
  * </ul>
  *
@@ -173,7 +172,7 @@ public final class Lucene90FieldInfosFormat extends FieldInfosFormat {
             pointNumBytes = 0;
           }
           final int vectorDimension = input.readVInt();
-          final VectorValues.SearchStrategy vectorDistFunc = getDistFunc(input, input.readByte());
+          final SimilarityFunction vectorDistFunc = getDistFunc(input, input.readByte());
 
           try {
             infos[i] =
@@ -254,12 +253,11 @@ public final class Lucene90FieldInfosFormat extends FieldInfosFormat {
     }
   }
 
-  private static VectorValues.SearchStrategy getDistFunc(IndexInput input, byte b)
-      throws IOException {
-    if (b < 0 || b >= VectorValues.SearchStrategy.values().length) {
+  private static SimilarityFunction getDistFunc(IndexInput input, byte b) throws IOException {
+    if (b < 0 || b >= SimilarityFunction.values().length) {
       throw new CorruptIndexException("invalid distance function: " + b, input);
     }
-    return VectorValues.SearchStrategy.values()[b];
+    return SimilarityFunction.values()[b];
   }
 
   static {
@@ -348,7 +346,7 @@ public final class Lucene90FieldInfosFormat extends FieldInfosFormat {
           output.writeVInt(fi.getPointNumBytes());
         }
         output.writeVInt(fi.getVectorDimension());
-        output.writeByte((byte) fi.getVectorSearchStrategy().ordinal());
+        output.writeByte((byte) fi.getVectorSimilarityFunction().ordinal());
       }
       CodecUtil.writeFooter(output);
     }

lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90VectorFormat.java

@@ -50,7 +50,7 @@ import org.apache.lucene.index.SegmentWriteState;
  *
  * <ul>
  *   <li><b>[int32]</b> field number
- *   <li><b>[int32]</b> vector search strategy ordinal
+ *   <li><b>[int32]</b> vector similarity function ordinal
  *   <li><b>[vlong]</b> offset to this field's vectors in the .vec file
  *   <li><b>[vlong]</b> length of this field's vectors, in bytes
  *   <li><b>[vlong]</b> offset to this field's index in the .vex file

lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90VectorReader.java

@@ -187,24 +187,28 @@ public final class Lucene90VectorReader extends VectorReader {
     }
   }
 
-  private VectorValues.SearchStrategy readSearchStrategy(DataInput input) throws IOException {
-    int searchStrategyId = input.readInt();
-    if (searchStrategyId < 0 || searchStrategyId >= VectorValues.SearchStrategy.values().length) {
-      throw new CorruptIndexException("Invalid search strategy id: " + searchStrategyId, input);
+  private VectorValues.SimilarityFunction readSimilarityFunction(DataInput input)
+      throws IOException {
+    int similarityFunctionId = input.readInt();
+    if (similarityFunctionId < 0
+        || similarityFunctionId >= VectorValues.SimilarityFunction.values().length) {
+      throw new CorruptIndexException(
+          "Invalid similarity function id: " + similarityFunctionId, input);
     }
-    return VectorValues.SearchStrategy.values()[searchStrategyId];
+    return VectorValues.SimilarityFunction.values()[similarityFunctionId];
   }
 
   private FieldEntry readField(DataInput input) throws IOException {
-    VectorValues.SearchStrategy searchStrategy = readSearchStrategy(input);
-    switch (searchStrategy) {
+    VectorValues.SimilarityFunction similarityFunction = readSimilarityFunction(input);
+    switch (similarityFunction) {
       case NONE:
-        return new FieldEntry(input, searchStrategy);
-      case DOT_PRODUCT_HNSW:
-      case EUCLIDEAN_HNSW:
-        return new HnswGraphFieldEntry(input, searchStrategy);
+        return new FieldEntry(input, similarityFunction);
+      case DOT_PRODUCT:
+      case EUCLIDEAN:
+        return new HnswGraphFieldEntry(input, similarityFunction);
       default:
-        throw new CorruptIndexException("Unknown vector search strategy: " + searchStrategy, input);
+        throw new CorruptIndexException(
+            "Unknown vector similarity function: " + similarityFunction, input);
     }
   }
 
@@ -288,7 +292,7 @@ public final class Lucene90VectorReader extends VectorReader {
   }
 
   private KnnGraphValues getGraphValues(FieldEntry entry) throws IOException {
-    if (entry.searchStrategy.isHnsw()) {
+    if (entry.similarityFunction.isHnsw()) {
       HnswGraphFieldEntry graphEntry = (HnswGraphFieldEntry) entry;
       IndexInput bytesSlice =
           vectorIndex.slice("graph-data", entry.indexDataOffset, entry.indexDataLength);
@@ -306,7 +310,7 @@ public final class Lucene90VectorReader extends VectorReader {
   private static class FieldEntry {
 
     final int dimension;
-    final VectorValues.SearchStrategy searchStrategy;
+    final VectorValues.SimilarityFunction similarityFunction;
 
     final long vectorDataOffset;
     final long vectorDataLength;
@@ -314,8 +318,9 @@ public final class Lucene90VectorReader extends VectorReader {
     final long indexDataLength;
     final int[] ordToDoc;
 
-    FieldEntry(DataInput input, VectorValues.SearchStrategy searchStrategy) throws IOException {
-      this.searchStrategy = searchStrategy;
+    FieldEntry(DataInput input, VectorValues.SimilarityFunction similarityFunction)
+        throws IOException {
+      this.similarityFunction = similarityFunction;
       vectorDataOffset = input.readVLong();
       vectorDataLength = input.readVLong();
       indexDataOffset = input.readVLong();
@@ -338,9 +343,9 @@ public final class Lucene90VectorReader extends VectorReader {
 
     final long[] ordOffsets;
 
-    HnswGraphFieldEntry(DataInput input, VectorValues.SearchStrategy searchStrategy)
+    HnswGraphFieldEntry(DataInput input, VectorValues.SimilarityFunction similarityFunction)
         throws IOException {
-      super(input, searchStrategy);
+      super(input, similarityFunction);
       ordOffsets = new long[size()];
       long offset = 0;
       for (int i = 0; i < ordOffsets.length; i++) {
@@ -385,8 +390,8 @@ public final class Lucene90VectorReader extends VectorReader {
     }
 
     @Override
-    public SearchStrategy searchStrategy() {
-      return fieldEntry.searchStrategy;
+    public SimilarityFunction similarityFunction() {
+      return fieldEntry.similarityFunction;
     }
 
     @Override
@@ -425,7 +430,7 @@ public final class Lucene90VectorReader extends VectorReader {
       if (ord < 0) {
         ord = -(ord + 1);
       }
-      assert ord >= 0 && ord <= fieldEntry.ordToDoc.length;
+      assert ord <= fieldEntry.ordToDoc.length;
       if (ord == fieldEntry.ordToDoc.length) {
         doc = NO_MORE_DOCS;
       } else {

lucene/core/src/java/org/apache/lucene/codecs/lucene90/Lucene90VectorWriter.java

@@ -121,7 +121,7 @@ public final class Lucene90VectorWriter extends VectorWriter {
     long[] offsets = new long[count];
     long vectorDataLength = vectorData.getFilePointer() - vectorDataOffset;
     long vectorIndexOffset = vectorIndex.getFilePointer();
-    if (vectors.searchStrategy().isHnsw()) {
+    if (vectors.similarityFunction().isHnsw()) {
       if (vectors instanceof RandomAccessVectorValuesProducer) {
         writeGraph(
             vectorIndex,
@@ -146,7 +146,7 @@ public final class Lucene90VectorWriter extends VectorWriter {
           vectorIndexLength,
           count,
           docIds);
-      if (vectors.searchStrategy().isHnsw()) {
+      if (vectors.similarityFunction().isHnsw()) {
         writeGraphOffsets(meta, offsets);
       }
     }
@@ -162,7 +162,7 @@ public final class Lucene90VectorWriter extends VectorWriter {
       int[] docIds)
       throws IOException {
     meta.writeInt(field.number);
-    meta.writeInt(field.getVectorSearchStrategy().ordinal());
+    meta.writeInt(field.getVectorSimilarityFunction().ordinal());
     meta.writeVLong(vectorDataOffset);
     meta.writeVLong(vectorDataLength);
     meta.writeVLong(indexDataOffset);

lucene/core/src/java/org/apache/lucene/document/FieldType.java

@@ -42,7 +42,8 @@ public class FieldType implements IndexableFieldType {
   private int indexDimensionCount;
   private int dimensionNumBytes;
   private int vectorDimension;
-  private VectorValues.SearchStrategy vectorSearchStrategy = VectorValues.SearchStrategy.NONE;
+  private VectorValues.SimilarityFunction vectorSimilarityFunction =
+      VectorValues.SimilarityFunction.NONE;
   private Map<String, String> attributes;
 
   /** Create a new mutable FieldType with all of the properties from <code>ref</code> */
@@ -60,7 +61,7 @@ public class FieldType implements IndexableFieldType {
     this.indexDimensionCount = ref.pointIndexDimensionCount();
     this.dimensionNumBytes = ref.pointNumBytes();
     this.vectorDimension = ref.vectorDimension();
-    this.vectorSearchStrategy = ref.vectorSearchStrategy();
+    this.vectorSimilarityFunction = ref.vectorSimilarityFunction();
     if (ref.getAttributes() != null) {
       this.attributes = new HashMap<>(ref.getAttributes());
     }
@@ -369,8 +370,8 @@ public class FieldType implements IndexableFieldType {
   }
 
   /** Enable vector indexing, with the specified number of dimensions and distance function. */
-  public void setVectorDimensionsAndSearchStrategy(
-      int numDimensions, VectorValues.SearchStrategy distFunc) {
+  public void setVectorDimensionsAndSimilarityFunction(
+      int numDimensions, VectorValues.SimilarityFunction distFunc) {
     checkIfFrozen();
     if (numDimensions <= 0) {
       throw new IllegalArgumentException("vector numDimensions must be > 0; got " + numDimensions);
@@ -383,7 +384,7 @@ public class FieldType implements IndexableFieldType {
               + numDimensions);
     }
     this.vectorDimension = numDimensions;
-    this.vectorSearchStrategy = distFunc;
+    this.vectorSimilarityFunction = distFunc;
   }
 
   @Override
@@ -392,8 +393,8 @@ public class FieldType implements IndexableFieldType {
   }
 
   @Override
-  public VectorValues.SearchStrategy vectorSearchStrategy() {
-    return vectorSearchStrategy;
+  public VectorValues.SimilarityFunction vectorSimilarityFunction() {
+    return vectorSimilarityFunction;
   }
 
   /**

lucene/core/src/java/org/apache/lucene/document/VectorField.java

@@ -25,15 +25,17 @@ import org.apache.lucene.util.hnsw.HnswGraphBuilder;
  * are dense - that is, every dimension of a vector contains an explicit value, stored packed into
  * an array (of type float[]) whose length is the vector dimension. Values can be retrieved using
  * {@link VectorValues}, which is a forward-only docID-based iterator and also offers random-access
- * by dense ordinal (not docId). VectorValues.SearchStrategys may be used to compare vectors at
+ * by dense ordinal (not docId). VectorValues.SearchSimlarity may be used to compare vectors at
  * query time (for example as part of result ranking). A VectorField may be associated with a search
- * strategy that defines the metric used for nearest-neighbor search among vectors of that field,
- * but at the moment this association is purely nominal: it is intended for future use by the
- * to-be-implemented nearest neighbors search.
+ * similarity function defining the metric used for nearest-neighbor search among vectors of that
+ * field.
+ *
+ * @lucene.experimental
  */
 public class VectorField extends Field {
 
-  private static FieldType createType(float[] v, VectorValues.SearchStrategy searchStrategy) {
+  private static FieldType createType(
+      float[] v, VectorValues.SimilarityFunction similarityFunction) {
     if (v == null) {
       throw new IllegalArgumentException("vector value must not be null");
     }
@@ -45,11 +47,11 @@ public class VectorField extends Field {
       throw new IllegalArgumentException(
           "cannot index vectors with dimension greater than " + VectorValues.MAX_DIMENSIONS);
     }
-    if (searchStrategy == null) {
-      throw new IllegalArgumentException("search strategy must not be null");
+    if (similarityFunction == null) {
+      throw new IllegalArgumentException("similarity function must not be null");
     }
     FieldType type = new FieldType();
-    type.setVectorDimensionsAndSearchStrategy(dimension, searchStrategy);
+    type.setVectorDimensionsAndSimilarityFunction(dimension, similarityFunction);
     type.freeze();
     return type;
   }
@@ -59,13 +61,16 @@ public class VectorField extends Field {
    * parameters that would be used by HnswGraphBuilder while constructing HNSW graph.
    *
    * @param dimension dimension of vectors
-   * @param searchStrategy a function defining vector proximity.
+   * @param similarityFunction a function defining vector proximity.
    * @param maxConn max-connections at each HNSW graph node
    * @param beamWidth size of list to be used while constructing HNSW graph
    * @throws IllegalArgumentException if any parameter is null, or has dimension > 1024.
    */
   public static FieldType createHnswType(
-      int dimension, VectorValues.SearchStrategy searchStrategy, int maxConn, int beamWidth) {
+      int dimension,
+      VectorValues.SimilarityFunction similarityFunction,
+      int maxConn,
+      int beamWidth) {
     if (dimension == 0) {
       throw new IllegalArgumentException("cannot index an empty vector");
     }
@@ -73,12 +78,12 @@ public class VectorField extends Field {
       throw new IllegalArgumentException(
           "cannot index vectors with dimension greater than " + VectorValues.MAX_DIMENSIONS);
     }
-    if (searchStrategy == null || !searchStrategy.isHnsw()) {
+    if (similarityFunction == null || !similarityFunction.isHnsw()) {
       throw new IllegalArgumentException(
-          "search strategy must not be null or non HNSW type, received: " + searchStrategy);
+          "similarity function must not be null, received: " + similarityFunction);
     }
     FieldType type = new FieldType();
-    type.setVectorDimensionsAndSearchStrategy(dimension, searchStrategy);
+    type.setVectorDimensionsAndSimilarityFunction(dimension, similarityFunction);
     type.putAttribute(HnswGraphBuilder.HNSW_MAX_CONN_ATTRIBUTE_KEY, String.valueOf(maxConn));
     type.putAttribute(HnswGraphBuilder.HNSW_BEAM_WIDTH_ATTRIBUTE_KEY, String.valueOf(beamWidth));
     type.freeze();
@@ -87,25 +92,26 @@ public class VectorField extends Field {
 
   /**
    * Creates a numeric vector field. Fields are single-valued: each document has either one value or
-   * no value. Vectors of a single field share the same dimension and search strategy. Note that
+   * no value. Vectors of a single field share the same dimension and similarity function. Note that
    * some strategies (notably dot-product) require values to be unit-length, which can be enforced
    * using VectorUtil.l2Normalize(float[]).
    *
    * @param name field name
    * @param vector value
-   * @param searchStrategy a function defining vector proximity.
+   * @param similarityFunction a function defining vector proximity.
    * @throws IllegalArgumentException if any parameter is null, or the vector is empty or has
    *     dimension > 1024.
    */
-  public VectorField(String name, float[] vector, VectorValues.SearchStrategy searchStrategy) {
-    super(name, createType(vector, searchStrategy));
+  public VectorField(
+      String name, float[] vector, VectorValues.SimilarityFunction similarityFunction) {
+    super(name, createType(vector, similarityFunction));
     fieldsData = vector;
   }
 
   /**
-   * Creates a numeric vector field with the default EUCLIDEAN_HNSW (L2) search strategy. Fields are
+   * Creates a numeric vector field with the default EUCLIDEAN_HNSW (L2) similarity. Fields are
    * single-valued: each document has either one value or no value. Vectors of a single field share
-   * the same dimension and search strategy.
+   * the same dimension and similarity function.
    *
    * @param name field name
    * @param vector value
@@ -113,12 +119,12 @@ public class VectorField extends Field {
    *     dimension > 1024.
    */
   public VectorField(String name, float[] vector) {
-    this(name, vector, VectorValues.SearchStrategy.EUCLIDEAN_HNSW);
+    this(name, vector, VectorValues.SimilarityFunction.EUCLIDEAN);
   }
 
   /**
    * Creates a numeric vector field. Fields are single-valued: each document has either one value or
-   * no value. Vectors of a single field share the same dimension and search strategy.
+   * no value. Vectors of a single field share the same dimension and similarity function.
    *
    * @param name field name
    * @param vector value

lucene/core/src/java/org/apache/lucene/index/CheckIndex.java

@@ -38,6 +38,8 @@ import org.apache.lucene.codecs.PointsReader;
 import org.apache.lucene.codecs.PostingsFormat;
 import org.apache.lucene.codecs.StoredFieldsReader;
 import org.apache.lucene.codecs.TermVectorsReader;
+import org.apache.lucene.codecs.VectorReader;
+import org.apache.lucene.codecs.lucene90.Lucene90VectorReader;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.DocumentStoredFieldVisitor;
 import org.apache.lucene.index.CheckIndex.Status.DocValuesStatus;
@@ -2336,6 +2338,29 @@ public final class CheckIndex implements Closeable {
                       + docCount
                       + " docs with values");
             }
+            VectorReader vectorReader = reader.getVectorReader();
+            if (vectorReader instanceof Lucene90VectorReader) {
+              KnnGraphValues graphValues =
+                  ((Lucene90VectorReader) vectorReader).getGraphValues(fieldInfo.name);
+              int size = graphValues.size();
+              for (int i = 0; i < size; i++) {
+                graphValues.seek(i);
+                for (int neighbor = graphValues.nextNeighbor();
+                    neighbor != NO_MORE_DOCS;
+                    neighbor = graphValues.nextNeighbor()) {
+                  if (neighbor < 0 || neighbor >= size) {
+                    throw new RuntimeException(
+                        "Field \""
+                            + fieldInfo.name
+                            + "\" has an invalid neighbor ordinal: "
+                            + neighbor
+                            + " which should be in [0,"
+                            + size
+                            + ")");
+                  }
+                }
+              }
+            }
             status.totalVectorValues += docCount;
           }
         }

lucene/core/src/java/org/apache/lucene/index/FieldInfo.java

@@ -56,7 +56,7 @@ public final class FieldInfo {
 
   // if it is a positive value, it means this field indexes vectors
   private final int vectorDimension;
-  private final VectorValues.SearchStrategy vectorSearchStrategy;
+  private final VectorValues.SimilarityFunction vectorSimilarityFunction;
 
   // whether this field is used as the soft-deletes field
   private final boolean softDeletesField;
@@ -80,7 +80,7 @@ public final class FieldInfo {
       int pointIndexDimensionCount,
       int pointNumBytes,
       int vectorDimension,
-      VectorValues.SearchStrategy vectorSearchStrategy,
+      VectorValues.SimilarityFunction vectorSimilarityFunction,
       boolean softDeletesField) {
     this.name = Objects.requireNonNull(name);
     this.number = number;
@@ -105,7 +105,7 @@ public final class FieldInfo {
     this.pointIndexDimensionCount = pointIndexDimensionCount;
     this.pointNumBytes = pointNumBytes;
     this.vectorDimension = vectorDimension;
-    this.vectorSearchStrategy = vectorSearchStrategy;
+    this.vectorSimilarityFunction = vectorSimilarityFunction;
     this.softDeletesField = softDeletesField;
     this.checkConsistency();
   }
@@ -194,18 +194,18 @@ public final class FieldInfo {
               + "')");
     }
 
-    if (vectorSearchStrategy == null) {
+    if (vectorSimilarityFunction == null) {
       throw new IllegalArgumentException(
-          "Vector search strategy must not be null (field: '" + name + "')");
+          "Vector similarity function must not be null (field: '" + name + "')");
     }
     if (vectorDimension < 0) {
       throw new IllegalArgumentException(
           "vectorDimension must be >=0; got " + vectorDimension + " (field: '" + name + "')");
     }
-    if (vectorDimension == 0 && vectorSearchStrategy != VectorValues.SearchStrategy.NONE) {
+    if (vectorDimension == 0 && vectorSimilarityFunction != VectorValues.SimilarityFunction.NONE) {
       throw new IllegalArgumentException(
-          "vector search strategy must be NONE when dimension = 0; got "
-              + vectorSearchStrategy
+          "vector similarity function must be NONE when dimension = 0; got "
+              + vectorSimilarityFunction
               + " (field: '"
               + name
               + "')");
@@ -237,9 +237,9 @@ public final class FieldInfo {
     verifySameVectorOptions(
         fieldName,
         this.vectorDimension,
-        this.vectorSearchStrategy,
+        this.vectorSimilarityFunction,
         o.vectorDimension,
-        o.vectorSearchStrategy);
+        o.vectorSimilarityFunction);
   }
 
   /**
@@ -355,21 +355,21 @@ public final class FieldInfo {
   static void verifySameVectorOptions(
       String fieldName,
       int vd1,
-      VectorValues.SearchStrategy vst1,
+      VectorValues.SimilarityFunction vsf1,
       int vd2,
-      VectorValues.SearchStrategy vst2) {
-    if (vd1 != vd2 || vst1 != vst2) {
+      VectorValues.SimilarityFunction vsf2) {
+    if (vd1 != vd2 || vsf1 != vsf2) {
       throw new IllegalArgumentException(
           "cannot change field \""
               + fieldName
               + "\" from vector dimension="
               + vd1
-              + ", vector search strategy="
-              + vst1
+              + ", vector similarity function="
+              + vsf1
               + " to inconsistent vector dimension="
               + vd2
-              + ", vector search strategy="
-              + vst2);
+              + ", vector similarity function="
+              + vsf2);
     }
   }
 
@@ -478,9 +478,9 @@ public final class FieldInfo {
     return vectorDimension;
   }
 
-  /** Returns {@link VectorValues.SearchStrategy} for the field */
-  public VectorValues.SearchStrategy getVectorSearchStrategy() {
-    return vectorSearchStrategy;
+  /** Returns {@link VectorValues.SimilarityFunction} for the field */
+  public VectorValues.SimilarityFunction getVectorSimilarityFunction() {
+    return vectorSimilarityFunction;
   }
 
   /** Record that this field is indexed with docvalues, with the specified type */

lucene/core/src/java/org/apache/lucene/index/FieldInfos.java

@@ -299,11 +299,11 @@ public class FieldInfos implements Iterable<FieldInfo> {
 
   static final class FieldVectorProperties {
     final int numDimensions;
-    final VectorValues.SearchStrategy searchStrategy;
+    final VectorValues.SimilarityFunction similarityFunction;
 
-    FieldVectorProperties(int numDimensions, VectorValues.SearchStrategy searchStrategy) {
+    FieldVectorProperties(int numDimensions, VectorValues.SimilarityFunction similarityFunction) {
       this.numDimensions = numDimensions;
-      this.searchStrategy = searchStrategy;
+      this.similarityFunction = similarityFunction;
     }
   }
 
@@ -384,7 +384,7 @@ public class FieldInfos implements Iterable<FieldInfo> {
                 fi.getPointNumBytes()));
         vectorProps.put(
             fieldName,
-            new FieldVectorProperties(fi.getVectorDimension(), fi.getVectorSearchStrategy()));
+            new FieldVectorProperties(fi.getVectorDimension(), fi.getVectorSimilarityFunction()));
       }
       return fieldNumber.intValue();
     }
@@ -442,9 +442,9 @@ public class FieldInfos implements Iterable<FieldInfo> {
       verifySameVectorOptions(
           fieldName,
           props.numDimensions,
-          props.searchStrategy,
+          props.similarityFunction,
           fi.getVectorDimension(),
-          fi.getVectorSearchStrategy());
+          fi.getVectorSimilarityFunction());
     }
 
     /**
@@ -486,7 +486,7 @@ public class FieldInfos implements Iterable<FieldInfo> {
                   0,
                   0,
                   0,
-                  VectorValues.SearchStrategy.NONE,
+                  VectorValues.SimilarityFunction.NONE,
                   (softDeletesFieldName != null && softDeletesFieldName.equals(fieldName)));
           addOrGet(fi);
         }
@@ -567,7 +567,7 @@ public class FieldInfos implements Iterable<FieldInfo> {
           0,
           0,
           0,
-          VectorValues.SearchStrategy.NONE,
+          VectorValues.SimilarityFunction.NONE,
           isSoftDeletesField);
     }
 
@@ -678,7 +678,7 @@ public class FieldInfos implements Iterable<FieldInfo> {
               fi.getPointIndexDimensionCount(),
               fi.getPointNumBytes(),
               fi.getVectorDimension(),
-              fi.getVectorSearchStrategy(),
+              fi.getVectorSimilarityFunction(),
               fi.isSoftDeletesField());
       byName.put(fiNew.getName(), fiNew);
       return fiNew;

lucene/core/src/java/org/apache/lucene/index/IndexableFieldType.java

@@ -101,8 +101,8 @@ public interface IndexableFieldType {
   /** The number of dimensions of the field's vector value */
   int vectorDimension();
 
-  /** The {@link VectorValues.SearchStrategy} of the field's vector value */
-  VectorValues.SearchStrategy vectorSearchStrategy();
+  /** The {@link VectorValues.SimilarityFunction} of the field's vector value */
+  VectorValues.SimilarityFunction vectorSimilarityFunction();
 
   /**
    * Attributes for the field type.

lucene/core/src/java/org/apache/lucene/index/IndexingChain.java

@@ -679,7 +679,7 @@ final class IndexingChain implements Accountable {
                 s.pointIndexDimensionCount,
                 s.pointNumBytes,
                 s.vectorDimension,
-                s.vectorSearchStrategy,
+                s.vectorSimilarityFunction,
                 pf.fieldName.equals(fieldInfos.getSoftDeletesFieldName())));
     pf.setFieldInfo(fi);
     if (fi.getIndexOptions() != IndexOptions.NONE) {
@@ -822,7 +822,7 @@ final class IndexingChain implements Accountable {
           fieldType.pointNumBytes());
     }
     if (fieldType.vectorDimension() != 0) {
-      schema.setVectors(fieldType.vectorSearchStrategy(), fieldType.vectorDimension());
+      schema.setVectors(fieldType.vectorSimilarityFunction(), fieldType.vectorDimension());
     }
     if (fieldType.getAttributes() != null && fieldType.getAttributes().isEmpty() == false) {
       schema.updateAttributes(fieldType.getAttributes());
@@ -1324,7 +1324,8 @@ final class IndexingChain implements Accountable {
     private int pointIndexDimensionCount = 0;
     private int pointNumBytes = 0;
     private int vectorDimension = 0;
-    private VectorValues.SearchStrategy vectorSearchStrategy = VectorValues.SearchStrategy.NONE;
+    private VectorValues.SimilarityFunction vectorSimilarityFunction =
+        VectorValues.SimilarityFunction.NONE;
 
     private static String errMsg =
         "Inconsistency of field data structures across documents for field ";
@@ -1379,12 +1380,12 @@ final class IndexingChain implements Accountable {
       }
     }
 
-    void setVectors(VectorValues.SearchStrategy searchStrategy, int dimension) {
-      if (vectorSearchStrategy == VectorValues.SearchStrategy.NONE) {
+    void setVectors(VectorValues.SimilarityFunction similarityFunction, int dimension) {
+      if (vectorSimilarityFunction == VectorValues.SimilarityFunction.NONE) {
         this.vectorDimension = dimension;
-        this.vectorSearchStrategy = searchStrategy;
+        this.vectorSimilarityFunction = similarityFunction;
       } else {
-        assertSame(vectorSearchStrategy == searchStrategy && vectorDimension == dimension);
+        assertSame(vectorSimilarityFunction == similarityFunction && vectorDimension == dimension);
       }
     }
 
@@ -1399,7 +1400,7 @@ final class IndexingChain implements Accountable {
       pointIndexDimensionCount = 0;
       pointNumBytes = 0;
       vectorDimension = 0;
-      vectorSearchStrategy = VectorValues.SearchStrategy.NONE;
+      vectorSimilarityFunction = VectorValues.SimilarityFunction.NONE;
     }
 
     void assertSameSchema(FieldInfo fi) {
@@ -1413,7 +1414,7 @@ final class IndexingChain implements Accountable {
               && pointIndexDimensionCount == fi.getPointIndexDimensionCount()
               && pointNumBytes == fi.getPointNumBytes()
               && vectorDimension == fi.getVectorDimension()
-              && vectorSearchStrategy == fi.getVectorSearchStrategy());
+              && vectorSimilarityFunction == fi.getVectorSimilarityFunction());
     }
   }
 }

lucene/core/src/java/org/apache/lucene/index/RandomAccessVectorValues.java

@@ -33,8 +33,8 @@ public interface RandomAccessVectorValues {
   /** Return the dimension of the returned vector values */
   int dimension();
 
-  /** Return the search strategy used to compare these vectors */
-  VectorValues.SearchStrategy searchStrategy();
+  /** Return the similarity function used to compare these vectors */
+  VectorValues.SimilarityFunction similarityFunction();
 
   /**
    * Return the vector value indexed at the given ordinal. The provided floating point array may be

lucene/core/src/java/org/apache/lucene/index/ReadersAndUpdates.java

@@ -722,7 +722,7 @@ final class ReadersAndUpdates {
         fi.getPointIndexDimensionCount(),
         fi.getPointNumBytes(),
         fi.getVectorDimension(),
-        fi.getVectorSearchStrategy(),
+        fi.getVectorSimilarityFunction(),
         fi.isSoftDeletesField());
   }
 

lucene/core/src/java/org/apache/lucene/index/VectorValues.java

@@ -51,8 +51,8 @@ public abstract class VectorValues extends DocIdSetIterator {
    */
   public abstract int size();
 
-  /** Return the search strategy used to compare these vectors */
-  public abstract SearchStrategy searchStrategy();
+  /** Return the similarity function used to compare these vectors */
+  public abstract SimilarityFunction similarityFunction();
 
   /**
    * Return the vector value for the current document ID. It is illegal to call this method when the
@@ -76,35 +76,36 @@ public abstract class VectorValues extends DocIdSetIterator {
   }
 
   /**
-   * Search strategy. This is a label describing the method used during indexing and searching of
-   * the vectors in order to determine the nearest neighbors.
+   * Vector similarity function; used in search to return top K most similar vectors to a target
+   * vector. This is a label describing the method used during indexing and searching of the vectors
+   * in order to determine the nearest neighbors.
    */
-  public enum SearchStrategy {
+  public enum SimilarityFunction {
 
     /**
-     * No search strategy is provided. Note: {@link VectorReader#search(String, float[], int, int)}
-     * is not supported for fields specifying this strategy.
+     * No similarity function is provided. Note: {@link VectorReader#search(float[], int, int)} is
+     * not supported for fields specifying this.
      */
     NONE,
 
     /** HNSW graph built using Euclidean distance */
-    EUCLIDEAN_HNSW(true),
+    EUCLIDEAN(true),
 
     /** HNSW graph buit using dot product */
-    DOT_PRODUCT_HNSW;
+    DOT_PRODUCT;
 
     /**
-     * If true, the scores associated with vector comparisons in this strategy are in reverse order;
-     * that is, lower scores represent more similar vectors. Otherwise, if false, higher scores
-     * represent more similar vectors.
+     * If true, the scores associated with vector comparisons are in reverse order; that is, lower
+     * scores represent more similar vectors. Otherwise, if false, higher scores represent more
+     * similar vectors.
      */
     public final boolean reversed;
 
-    SearchStrategy(boolean reversed) {
+    SimilarityFunction(boolean reversed) {
       this.reversed = reversed;
     }
 
-    SearchStrategy() {
+    SimilarityFunction() {
       reversed = false;
     }
 
@@ -113,25 +114,25 @@ public abstract class VectorValues extends DocIdSetIterator {
      *
      * @param v1 a vector
      * @param v2 another vector, of the same dimension
-     * @return the value of the strategy's score function applied to the two vectors
+     * @return the value of the similarity function applied to the two vectors
      */
     public float compare(float[] v1, float[] v2) {
       switch (this) {
-        case EUCLIDEAN_HNSW:
+        case EUCLIDEAN:
           return squareDistance(v1, v2);
-        case DOT_PRODUCT_HNSW:
+        case DOT_PRODUCT:
           return dotProduct(v1, v2);
         case NONE:
         default:
-          throw new IllegalStateException("Incomparable search strategy: " + this);
+          throw new IllegalStateException("Incomparable similarity function: " + this);
       }
     }
 
-    /** Return true if vectors indexed using this strategy will be indexed using an HNSW graph */
+    /** Return true if vectors indexed using this similarity will be indexed using an HNSW graph */
     public boolean isHnsw() {
       switch (this) {
-        case EUCLIDEAN_HNSW:
-        case DOT_PRODUCT_HNSW:
+        case EUCLIDEAN:
+        case DOT_PRODUCT:
           return true;
         case NONE:
         default:
@@ -158,8 +159,8 @@ public abstract class VectorValues extends DocIdSetIterator {
         }
 
         @Override
-        public SearchStrategy searchStrategy() {
-          return SearchStrategy.NONE;
+        public SimilarityFunction similarityFunction() {
+          return SimilarityFunction.NONE;
         }
 
         @Override

lucene/core/src/java/org/apache/lucene/index/VectorValuesWriter.java

@@ -29,7 +29,11 @@ import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.Counter;
 import org.apache.lucene.util.RamUsageEstimator;
 
-/** Buffers up pending vector value(s) per doc, then flushes when segment flushes. */
+/**
+ * Buffers up pending vector value(s) per doc, then flushes when segment flushes.
+ *
+ * @lucene.experimental
+ */
 class VectorValuesWriter {
 
   private final FieldInfo fieldInfo;
@@ -108,7 +112,7 @@ class VectorValuesWriter {
             docsWithField,
             vectors,
             fieldInfo.getVectorDimension(),
-            fieldInfo.getVectorSearchStrategy());
+            fieldInfo.getVectorSimilarityFunction());
     if (sortMap != null) {
       vectorWriter.writeField(fieldInfo, new SortingVectorValues(vectorValues, sortMap));
     } else {
@@ -186,8 +190,8 @@ class VectorValuesWriter {
     }
 
     @Override
-    public SearchStrategy searchStrategy() {
-      return delegate.searchStrategy();
+    public SimilarityFunction similarityFunction() {
+      return delegate.similarityFunction();
     }
 
     @Override
@@ -220,8 +224,8 @@ class VectorValuesWriter {
         }
 
         @Override
-        public SearchStrategy searchStrategy() {
-          return delegateRA.searchStrategy();
+        public SimilarityFunction similarityFunction() {
+          return delegateRA.similarityFunction();
         }
 
         @Override
@@ -244,7 +248,7 @@ class VectorValuesWriter {
 
     // These are always the vectors of a VectorValuesWriter, which are copied when added to it
     final List<float[]> vectors;
-    final SearchStrategy searchStrategy;
+    final SimilarityFunction similarityFunction;
     final int dimension;
 
     final ByteBuffer buffer;
@@ -259,11 +263,11 @@ class VectorValuesWriter {
         DocsWithFieldSet docsWithField,
         List<float[]> vectors,
         int dimension,
-        SearchStrategy searchStrategy) {
+        SimilarityFunction similarityFunction) {
       this.docsWithField = docsWithField;
       this.vectors = vectors;
       this.dimension = dimension;
-      this.searchStrategy = searchStrategy;
+      this.similarityFunction = similarityFunction;
       buffer = ByteBuffer.allocate(dimension * Float.BYTES).order(ByteOrder.LITTLE_ENDIAN);
       binaryValue = new BytesRef(buffer.array());
       raBuffer = ByteBuffer.allocate(dimension * Float.BYTES).order(ByteOrder.LITTLE_ENDIAN);
@@ -273,7 +277,7 @@ class VectorValuesWriter {
 
     @Override
     public RandomAccessVectorValues randomAccess() {
-      return new BufferedVectorValues(docsWithField, vectors, dimension, searchStrategy);
+      return new BufferedVectorValues(docsWithField, vectors, dimension, similarityFunction);
     }
 
     @Override
@@ -287,8 +291,8 @@ class VectorValuesWriter {
     }
 
     @Override
-    public SearchStrategy searchStrategy() {
-      return searchStrategy;
+    public SimilarityFunction similarityFunction() {
+      return similarityFunction;
     }
 
     @Override

lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraph.java

@@ -99,11 +99,11 @@ public final class HnswGraph extends KnnGraphValues {
       KnnGraphValues graphValues,
       Random random)
       throws IOException {
-    VectorValues.SearchStrategy searchStrategy = vectors.searchStrategy();
+    VectorValues.SimilarityFunction similarityFunction = vectors.similarityFunction();
     int size = graphValues.size();
 
     // MIN heap, holding the top results
-    NeighborQueue results = new NeighborQueue(numSeed, searchStrategy.reversed);
+    NeighborQueue results = new NeighborQueue(numSeed, similarityFunction.reversed);
 
     // set of ordinals that have been visited by search on this layer, used to avoid backtracking
     SparseFixedBitSet visited = new SparseFixedBitSet(size);
@@ -114,17 +114,17 @@ public final class HnswGraph extends KnnGraphValues {
       if (visited.get(entryPoint) == false) {
         visited.set(entryPoint);
         // explore the topK starting points of some random numSeed probes
-        results.add(entryPoint, searchStrategy.compare(query, vectors.vectorValue(entryPoint)));
+        results.add(entryPoint, similarityFunction.compare(query, vectors.vectorValue(entryPoint)));
       }
     }
 
     // MAX heap, from which to pull the candidate nodes
-    NeighborQueue candidates = results.copy(!searchStrategy.reversed);
+    NeighborQueue candidates = results.copy(!similarityFunction.reversed);
 
     // Set the bound to the worst current result and below reject any newly-generated candidates
     // failing
     // to exceed this bound
-    BoundsChecker bound = BoundsChecker.create(searchStrategy.reversed);
+    BoundsChecker bound = BoundsChecker.create(similarityFunction.reversed);
     bound.set(results.topScore());
     while (candidates.size() > 0) {
       // get the best candidate (closest or best scoring)
@@ -143,7 +143,7 @@ public final class HnswGraph extends KnnGraphValues {
           continue;
         }
         visited.set(friendOrd);
-        float score = searchStrategy.compare(query, vectors.vectorValue(friendOrd));
+        float score = similarityFunction.compare(query, vectors.vectorValue(friendOrd));
         if (results.insertWithOverflow(friendOrd, score)) {
           candidates.add(friendOrd, score);
           bound.set(results.topScore());

lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraphBuilder.java

@@ -54,7 +54,7 @@ public final class HnswGraphBuilder {
   private final int beamWidth;
   private final NeighborArray scratch;
 
-  private final VectorValues.SearchStrategy searchStrategy;
+  private final VectorValues.SimilarityFunction similarityFunction;
   private final RandomAccessVectorValues vectorValues;
   private final Random random;
   private final BoundsChecker bound;
@@ -87,8 +87,8 @@ public final class HnswGraphBuilder {
       RandomAccessVectorValuesProducer vectors, int maxConn, int beamWidth, long seed) {
     vectorValues = vectors.randomAccess();
     buildVectors = vectors.randomAccess();
-    searchStrategy = vectorValues.searchStrategy();
-    if (searchStrategy == VectorValues.SearchStrategy.NONE) {
+    similarityFunction = vectorValues.similarityFunction();
+    if (similarityFunction == VectorValues.SimilarityFunction.NONE) {
       throw new IllegalStateException("No distance function");
     }
     if (maxConn <= 0) {
@@ -100,7 +100,7 @@ public final class HnswGraphBuilder {
     this.maxConn = maxConn;
     this.beamWidth = beamWidth;
     this.hnsw = new HnswGraph(maxConn);
-    bound = BoundsChecker.create(searchStrategy.reversed);
+    bound = BoundsChecker.create(similarityFunction.reversed);
     random = new Random(seed);
     scratch = new NeighborArray(Math.max(beamWidth, maxConn + 1));
   }
@@ -232,7 +232,7 @@ public final class HnswGraphBuilder {
     bound.set(score);
     for (int i = 0; i < neighbors.size(); i++) {
       float diversityCheck =
-          searchStrategy.compare(candidate, vectorValues.vectorValue(neighbors.node[i]));
+          similarityFunction.compare(candidate, vectorValues.vectorValue(neighbors.node[i]));
       if (bound.check(diversityCheck) == false) {
         return false;
       }
@@ -269,7 +269,7 @@ public final class HnswGraphBuilder {
       float[] nbrVector = vectorValues.vectorValue(nbrNode);
       for (int j = maxConn; j > i; j--) {
         float diversityCheck =
-            searchStrategy.compare(nbrVector, buildVectors.vectorValue(neighbors.node[j]));
+            similarityFunction.compare(nbrVector, buildVectors.vectorValue(neighbors.node[j]));
         if (bound.check(diversityCheck) == false) {
           // node j is too similar to node i given its score relative to the base node
           // replace it with the new node, which is at [maxConn]

lucene/core/src/test/org/apache/lucene/document/TestPerFieldConsistency.java

@@ -87,16 +87,16 @@ public class TestPerFieldConsistency extends LuceneTestCase {
   }
 
   private static Field randomVectorField(Random random, String fieldName) {
-    VectorValues.SearchStrategy searchStrategy =
-        RandomPicks.randomFrom(random, VectorValues.SearchStrategy.values());
-    while (searchStrategy == VectorValues.SearchStrategy.NONE) {
-      searchStrategy = RandomPicks.randomFrom(random, VectorValues.SearchStrategy.values());
+    VectorValues.SimilarityFunction similarityFunction =
+        RandomPicks.randomFrom(random, VectorValues.SimilarityFunction.values());
+    while (similarityFunction == VectorValues.SimilarityFunction.NONE) {
+      similarityFunction = RandomPicks.randomFrom(random, VectorValues.SimilarityFunction.values());
     }
     float[] values = new float[randomIntBetween(1, 10)];
     for (int i = 0; i < values.length; i++) {
       values[i] = randomFloat();
     }
-    return new VectorField(fieldName, values, searchStrategy);
+    return new VectorField(fieldName, values, similarityFunction);
   }
 
   private static Field[] randomFieldsWithTheSameName(String fieldName) {

lucene/core/src/test/org/apache/lucene/index/TestCodecs.java

@@ -112,7 +112,7 @@ public class TestCodecs extends LuceneTestCase {
                     0,
                     0,
                     0,
-                    VectorValues.SearchStrategy.NONE,
+                    VectorValues.SimilarityFunction.NONE,
                     false));
       }
       this.terms = terms;

lucene/core/src/test/org/apache/lucene/index/TestFieldInfos.java

@@ -260,7 +260,7 @@ public class TestFieldInfos extends LuceneTestCase {
               0,
               0,
               0,
-              VectorValues.SearchStrategy.NONE,
+              VectorValues.SimilarityFunction.NONE,
               false));
     }
     int idx =
@@ -279,7 +279,7 @@ public class TestFieldInfos extends LuceneTestCase {
                 0,
                 0,
                 0,
-                VectorValues.SearchStrategy.NONE,
+                VectorValues.SimilarityFunction.NONE,
                 false));
     assertEquals("Field numbers 0 through 9 were allocated", 10, idx);
 
@@ -300,7 +300,7 @@ public class TestFieldInfos extends LuceneTestCase {
                 0,
                 0,
                 0,
-                VectorValues.SearchStrategy.NONE,
+                VectorValues.SimilarityFunction.NONE,
                 false));
     assertEquals("Field numbers should reset after clear()", 0, idx);
   }

lucene/core/src/test/org/apache/lucene/index/TestFieldsReader.java

@@ -63,7 +63,7 @@ public class TestFieldsReader extends LuceneTestCase {
               0,
               0,
               0,
-              VectorValues.SearchStrategy.NONE,
+              VectorValues.SimilarityFunction.NONE,
               field.name().equals(softDeletesFieldName)));
     }
     dir = newDirectory();

lucene/core/src/test/org/apache/lucene/index/TestIndexableField.java

@@ -113,8 +113,8 @@ public class TestIndexableField extends LuceneTestCase {
           }
 
           @Override
-          public VectorValues.SearchStrategy vectorSearchStrategy() {
-            return VectorValues.SearchStrategy.NONE;
+          public VectorValues.SimilarityFunction vectorSimilarityFunction() {
+            return VectorValues.SimilarityFunction.NONE;
           }
 
           @Override

lucene/core/src/test/org/apache/lucene/index/TestKnnGraph.java

@@ -34,7 +34,7 @@ import org.apache.lucene.document.FieldType;
 import org.apache.lucene.document.SortedDocValuesField;
 import org.apache.lucene.document.StringField;
 import org.apache.lucene.document.VectorField;
-import org.apache.lucene.index.VectorValues.SearchStrategy;
+import org.apache.lucene.index.VectorValues.SimilarityFunction;
 import org.apache.lucene.search.ScoreDoc;
 import org.apache.lucene.search.TopDocs;
 import org.apache.lucene.store.Directory;
@@ -53,7 +53,7 @@ public class TestKnnGraph extends LuceneTestCase {
 
   private static int maxConn = HnswGraphBuilder.DEFAULT_MAX_CONN;
 
-  private SearchStrategy searchStrategy;
+  private SimilarityFunction similarityFunction;
 
   @Before
   public void setup() {
@@ -61,8 +61,8 @@ public class TestKnnGraph extends LuceneTestCase {
     if (random().nextBoolean()) {
       maxConn = random().nextInt(256) + 3;
     }
-    int strategy = random().nextInt(SearchStrategy.values().length - 1) + 1;
-    searchStrategy = SearchStrategy.values()[strategy];
+    int similarity = random().nextInt(SimilarityFunction.values().length - 1) + 1;
+    similarityFunction = SimilarityFunction.values()[similarity];
   }
 
   @After
@@ -212,7 +212,7 @@ public class TestKnnGraph extends LuceneTestCase {
   /** Verify that searching does something reasonable */
   public void testSearch() throws Exception {
     // We can't use dot product here since the vectors are laid out on a grid, not a sphere.
-    searchStrategy = SearchStrategy.EUCLIDEAN_HNSW;
+    similarityFunction = SimilarityFunction.EUCLIDEAN;
     IndexWriterConfig config = newIndexWriterConfig();
     config.setCodec(Codec.forName("Lucene90")); // test is not compatible with simpletext
     try (Directory dir = newDirectory();
@@ -434,16 +434,16 @@ public class TestKnnGraph extends LuceneTestCase {
   }
 
   private void add(IndexWriter iw, int id, float[] vector) throws IOException {
-    add(iw, id, vector, searchStrategy);
+    add(iw, id, vector, similarityFunction);
   }
 
-  private void add(IndexWriter iw, int id, float[] vector, SearchStrategy searchStrategy)
+  private void add(IndexWriter iw, int id, float[] vector, SimilarityFunction similarityFunction)
       throws IOException {
     Document doc = new Document();
     if (vector != null) {
       FieldType fieldType =
           VectorField.createHnswType(
-              vector.length, searchStrategy, maxConn, HnswGraphBuilder.DEFAULT_BEAM_WIDTH);
+              vector.length, similarityFunction, maxConn, HnswGraphBuilder.DEFAULT_BEAM_WIDTH);
       doc.add(new VectorField(KNN_GRAPH_FIELD, vector, fieldType));
     }
     String idString = Integer.toString(id);

lucene/core/src/test/org/apache/lucene/index/TestPendingSoftDeletes.java

@@ -17,7 +17,7 @@
 
 package org.apache.lucene.index;
 
-import static org.apache.lucene.index.VectorValues.SearchStrategy.NONE;
+import static org.apache.lucene.index.VectorValues.SimilarityFunction.NONE;
 
 import java.io.IOException;
 import java.util.Arrays;

lucene/core/src/test/org/apache/lucene/util/hnsw/KnnGraphTester.java

@@ -70,8 +70,8 @@ public class KnnGraphTester {
 
   private static final String KNN_FIELD = "knn";
   private static final String ID_FIELD = "id";
-  private static final VectorValues.SearchStrategy SEARCH_STRATEGY =
-      VectorValues.SearchStrategy.DOT_PRODUCT_HNSW;
+  private static final VectorValues.SimilarityFunction SIMILARITY_FUNCTION =
+      VectorValues.SimilarityFunction.DOT_PRODUCT;
 
   private int numDocs;
   private int dim;
@@ -542,10 +542,10 @@ public class KnnGraphTester {
                   .order(ByteOrder.LITTLE_ENDIAN)
                   .asFloatBuffer();
           offset += blockSize;
-          NeighborQueue queue = new NeighborQueue(topK, SEARCH_STRATEGY.reversed);
+          NeighborQueue queue = new NeighborQueue(topK, SIMILARITY_FUNCTION.reversed);
           for (; j < numDocs && vectors.hasRemaining(); j++) {
             vectors.get(vector);
-            float d = SEARCH_STRATEGY.compare(query, vector);
+            float d = SIMILARITY_FUNCTION.compare(query, vector);
             queue.insertWithOverflow(j, d);
           }
           result[i] = new int[topK];
@@ -572,7 +572,7 @@ public class KnnGraphTester {
 
     FieldType fieldType =
         VectorField.createHnswType(
-            dim, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW, maxConn, beamWidth);
+            dim, VectorValues.SimilarityFunction.DOT_PRODUCT, maxConn, beamWidth);
     if (quiet == false) {
       iwc.setInfoStream(new PrintStreamInfoStream(System.out));
       System.out.println("creating index in " + indexPath);
@@ -667,8 +667,8 @@ public class KnnGraphTester {
       }
 
       @Override
-      public VectorValues.SearchStrategy searchStrategy() {
-        return SEARCH_STRATEGY;
+      public VectorValues.SimilarityFunction similarityFunction() {
+        return SIMILARITY_FUNCTION;
       }
 
       @Override

lucene/core/src/test/org/apache/lucene/util/hnsw/MockVectorValues.java

@@ -30,13 +30,13 @@ class MockVectorValues extends VectorValues
   protected final int dimension;
   protected final float[][] denseValues;
   protected final float[][] values;
-  protected final SearchStrategy searchStrategy;
+  protected final SimilarityFunction similarityFunction;
   private final int numVectors;
 
   private int pos = -1;
 
-  MockVectorValues(SearchStrategy searchStrategy, float[][] values) {
-    this.searchStrategy = searchStrategy;
+  MockVectorValues(SimilarityFunction similarityFunction, float[][] values) {
+    this.similarityFunction = similarityFunction;
     this.dimension = values[0].length;
     this.values = values;
     int maxDoc = values.length;
@@ -52,7 +52,7 @@ class MockVectorValues extends VectorValues
   }
 
   public MockVectorValues copy() {
-    return new MockVectorValues(searchStrategy, values);
+    return new MockVectorValues(similarityFunction, values);
   }
 
   @Override
@@ -61,8 +61,8 @@ class MockVectorValues extends VectorValues
   }
 
   @Override
-  public SearchStrategy searchStrategy() {
-    return searchStrategy;
+  public SimilarityFunction similarityFunction() {
+    return similarityFunction;
   }
 
   @Override

lucene/core/src/test/org/apache/lucene/util/hnsw/TestHnsw.java

@@ -73,7 +73,7 @@ public class TestHnsw extends LuceneTestCase {
             indexedDoc++;
           }
           Document doc = new Document();
-          doc.add(new VectorField("field", v2.vectorValue(), v2.searchStrategy));
+          doc.add(new VectorField("field", v2.vectorValue(), v2.similarityFunction));
           doc.add(new StoredField("id", v2.docID()));
           iw.addDocument(doc);
           nVec++;
@@ -83,7 +83,7 @@ public class TestHnsw extends LuceneTestCase {
       try (IndexReader reader = DirectoryReader.open(dir)) {
         for (LeafReaderContext ctx : reader.leaves()) {
           VectorValues values = ctx.reader().getVectorValues("field");
-          assertEquals(vectors.searchStrategy, values.searchStrategy());
+          assertEquals(vectors.similarityFunction, values.similarityFunction());
           assertEquals(dim, values.dimension());
           assertEquals(nVec, values.size());
           assertEquals(indexedDoc, ctx.reader().maxDoc());
@@ -164,7 +164,7 @@ public class TestHnsw extends LuceneTestCase {
     // Some carefully checked test cases with simple 2d vectors on the unit circle:
     MockVectorValues vectors =
         new MockVectorValues(
-            VectorValues.SearchStrategy.DOT_PRODUCT_HNSW,
+            VectorValues.SimilarityFunction.DOT_PRODUCT,
             new float[][] {
               unitVector2d(0.5),
               unitVector2d(0.75),
@@ -236,12 +236,12 @@ public class TestHnsw extends LuceneTestCase {
     for (int i = 0; i < 100; i++) {
       float[] query = randomVector(random(), dim);
       NeighborQueue actual = HnswGraph.search(query, topK, 100, vectors, hnsw, random());
-      NeighborQueue expected = new NeighborQueue(topK, vectors.searchStrategy.reversed);
+      NeighborQueue expected = new NeighborQueue(topK, vectors.similarityFunction.reversed);
       for (int j = 0; j < size; j++) {
         float[] v = vectors.vectorValue(j);
         if (v != null) {
           expected.insertWithOverflow(
-              j, vectors.searchStrategy.compare(query, vectors.vectorValue(j)));
+              j, vectors.similarityFunction.compare(query, vectors.vectorValue(j)));
         }
       }
       assertEquals(topK, actual.size());
@@ -288,8 +288,8 @@ public class TestHnsw extends LuceneTestCase {
     }
 
     @Override
-    public SearchStrategy searchStrategy() {
-      return SearchStrategy.DOT_PRODUCT_HNSW;
+    public SimilarityFunction similarityFunction() {
+      return SimilarityFunction.DOT_PRODUCT;
     }
 
     @Override
@@ -393,12 +393,12 @@ public class TestHnsw extends LuceneTestCase {
 
     RandomVectorValues(int size, int dimension, Random random) {
       super(
-          SearchStrategy.values()[random.nextInt(SearchStrategy.values().length - 1) + 1],
+          SimilarityFunction.values()[random.nextInt(SimilarityFunction.values().length - 1) + 1],
           createRandomVectors(size, dimension, random));
     }
 
     RandomVectorValues(RandomVectorValues other) {
-      super(other.searchStrategy, other.values);
+      super(other.similarityFunction, other.values);
     }
 
     @Override

lucene/core/src/test/org/apache/lucene/util/hnsw/TestNeighbors.java

@@ -107,7 +107,5 @@ public class TestNeighbors extends LuceneTestCase {
 
   public void testToString() {
     assertEquals("Neighbors[0]", new NeighborQueue(2, false).toString());
-    // assertEquals("NeighborArray[0]", new NeighborArray(2,
-    // VectorValues.SearchStrategy.NONE).toString());
   }
 }

lucene/highlighter/src/java/org/apache/lucene/search/highlight/TermVectorLeafReader.java

@@ -96,7 +96,7 @@ public class TermVectorLeafReader extends LeafReader {
             0,
             0,
             0,
-            VectorValues.SearchStrategy.NONE,
+            VectorValues.SimilarityFunction.NONE,
             false);
     fieldInfos = new FieldInfos(new FieldInfo[] {fieldInfo});
   }

lucene/memory/src/java/org/apache/lucene/index/memory/MemoryIndex.java

@@ -512,7 +512,7 @@ public class MemoryIndex {
         fieldType.pointIndexDimensionCount(),
         fieldType.pointNumBytes(),
         fieldType.vectorDimension(),
-        fieldType.vectorSearchStrategy(),
+        fieldType.vectorSimilarityFunction(),
         false);
   }
 
@@ -544,7 +544,7 @@ public class MemoryIndex {
               info.fieldInfo.getPointIndexDimensionCount(),
               info.fieldInfo.getPointNumBytes(),
               info.fieldInfo.getVectorDimension(),
-              info.fieldInfo.getVectorSearchStrategy(),
+              info.fieldInfo.getVectorSimilarityFunction(),
               info.fieldInfo.isSoftDeletesField());
     } else if (existingDocValuesType != docValuesType) {
       throw new IllegalArgumentException(

lucene/test-framework/src/java/org/apache/lucene/index/BaseFieldInfoFormatTestCase.java

@@ -295,7 +295,7 @@ public abstract class BaseFieldInfoFormatTestCase extends BaseIndexFileFormatTes
               fieldType.pointIndexDimensionCount(),
               fieldType.pointNumBytes(),
               fieldType.vectorDimension(),
-              fieldType.vectorSearchStrategy(),
+              fieldType.vectorSimilarityFunction(),
               field.equals(softDeletesField));
       addAttributes(fi);
       builder.add(fi);
@@ -341,9 +341,9 @@ public abstract class BaseFieldInfoFormatTestCase extends BaseIndexFileFormatTes
 
     if (r.nextBoolean()) {
       int dimension = 1 + r.nextInt(VectorValues.MAX_DIMENSIONS);
-      VectorValues.SearchStrategy searchStrategy =
-          RandomPicks.randomFrom(r, VectorValues.SearchStrategy.values());
-      type.setVectorDimensionsAndSearchStrategy(dimension, searchStrategy);
+      VectorValues.SimilarityFunction similarityFunction =
+          RandomPicks.randomFrom(r, VectorValues.SimilarityFunction.values());
+      type.setVectorDimensionsAndSimilarityFunction(dimension, similarityFunction);
     }
 
     return type;
@@ -412,7 +412,7 @@ public abstract class BaseFieldInfoFormatTestCase extends BaseIndexFileFormatTes
         0,
         0,
         0,
-        VectorValues.SearchStrategy.NONE,
+        VectorValues.SimilarityFunction.NONE,
         false);
   }
 }

lucene/test-framework/src/java/org/apache/lucene/index/BaseIndexFileFormatTestCase.java

@@ -335,7 +335,7 @@ abstract class BaseIndexFileFormatTestCase extends LuceneTestCase {
             proto.getPointIndexDimensionCount(),
             proto.getPointNumBytes(),
             proto.getVectorDimension(),
-            proto.getVectorSearchStrategy(),
+            proto.getVectorSimilarityFunction(),
             proto.isSoftDeletesField());
 
     FieldInfos fieldInfos = new FieldInfos(new FieldInfo[] {field});

lucene/test-framework/src/java/org/apache/lucene/index/BaseVectorFormatTestCase.java

@@ -49,7 +49,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
 
   @Override
   protected void addRandomFields(Document doc) {
-    doc.add(new VectorField("v2", randomVector(30), VectorValues.SearchStrategy.NONE));
+    doc.add(new VectorField("v2", randomVector(30), VectorValues.SimilarityFunction.NONE));
   }
 
   public void testFieldConstructor() {
@@ -57,7 +57,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     VectorField field = new VectorField("f", v);
     assertEquals(1, field.fieldType().vectorDimension());
     assertEquals(
-        VectorValues.SearchStrategy.EUCLIDEAN_HNSW, field.fieldType().vectorSearchStrategy());
+        VectorValues.SimilarityFunction.EUCLIDEAN, field.fieldType().vectorSimilarityFunction());
     assertSame(v, field.vectorValue());
   }
 
@@ -66,7 +66,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     expectThrows(IllegalArgumentException.class, () -> new VectorField("f", null));
     expectThrows(
         IllegalArgumentException.class,
-        () -> new VectorField("f", new float[1], (VectorValues.SearchStrategy) null));
+        () -> new VectorField("f", new float[1], (VectorValues.SimilarityFunction) null));
     expectThrows(IllegalArgumentException.class, () -> new VectorField("f", new float[0]));
     expectThrows(
         IllegalArgumentException.class,
@@ -88,13 +88,13 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
   public void testFieldCreateFieldType() {
     expectThrows(
         IllegalArgumentException.class,
-        () -> VectorField.createHnswType(0, VectorValues.SearchStrategy.EUCLIDEAN_HNSW, 16, 16));
+        () -> VectorField.createHnswType(0, VectorValues.SimilarityFunction.EUCLIDEAN, 16, 16));
     expectThrows(
         IllegalArgumentException.class,
         () ->
             VectorField.createHnswType(
                 VectorValues.MAX_DIMENSIONS + 1,
-                VectorValues.SearchStrategy.EUCLIDEAN_HNSW,
+                VectorValues.SimilarityFunction.EUCLIDEAN,
                 16,
                 16));
     expectThrows(
@@ -104,7 +104,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         IllegalArgumentException.class,
         () ->
             VectorField.createHnswType(
-                VectorValues.MAX_DIMENSIONS + 1, VectorValues.SearchStrategy.NONE, 16, 16));
+                VectorValues.MAX_DIMENSIONS + 1, VectorValues.SimilarityFunction.NONE, 16, 16));
   }
 
   // Illegal schema change tests:
@@ -113,11 +113,11 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory();
         IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc = new Document();
-      doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
 
       Document doc2 = new Document();
-      doc2.add(new VectorField("f", new float[3], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc2.add(new VectorField("f", new float[3], VectorValues.SimilarityFunction.DOT_PRODUCT));
       IllegalArgumentException expected =
           expectThrows(IllegalArgumentException.class, () -> w.addDocument(doc2));
       String errMsg =
@@ -129,31 +129,31 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory();
         IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc = new Document();
-      doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
       w.commit();
 
       Document doc2 = new Document();
-      doc2.add(new VectorField("f", new float[3], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc2.add(new VectorField("f", new float[3], VectorValues.SimilarityFunction.DOT_PRODUCT));
       IllegalArgumentException expected =
           expectThrows(IllegalArgumentException.class, () -> w.addDocument(doc2));
       String errMsg =
-          "cannot change field \"f\" from vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW "
-              + "to inconsistent vector dimension=3, vector search strategy=DOT_PRODUCT_HNSW";
+          "cannot change field \"f\" from vector dimension=4, vector similarity function=DOT_PRODUCT "
+              + "to inconsistent vector dimension=3, vector similarity function=DOT_PRODUCT";
       assertEquals(errMsg, expected.getMessage());
     }
   }
 
-  public void testIllegalSearchStrategyChange() throws Exception {
+  public void testIllegalSimilarityFunctionChange() throws Exception {
     // illegal change in the same segment
     try (Directory dir = newDirectory();
         IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc = new Document();
-      doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
 
       Document doc2 = new Document();
-      doc2.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+      doc2.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.EUCLIDEAN));
       IllegalArgumentException expected =
           expectThrows(IllegalArgumentException.class, () -> w.addDocument(doc2));
       String errMsg =
@@ -165,17 +165,17 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory();
         IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc = new Document();
-      doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
       w.commit();
 
       Document doc2 = new Document();
-      doc2.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+      doc2.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.EUCLIDEAN));
       IllegalArgumentException expected =
           expectThrows(IllegalArgumentException.class, () -> w.addDocument(doc2));
       String errMsg =
-          "cannot change field \"f\" from vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW "
-              + "to inconsistent vector dimension=4, vector search strategy=EUCLIDEAN_HNSW";
+          "cannot change field \"f\" from vector dimension=4, vector similarity function=DOT_PRODUCT "
+              + "to inconsistent vector dimension=4, vector similarity function=EUCLIDEAN";
       assertEquals(errMsg, expected.getMessage());
     }
   }
@@ -184,39 +184,39 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
 
       try (IndexWriter w2 = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc2 = new Document();
-        doc2.add(new VectorField("f", new float[1], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc2.add(new VectorField("f", new float[1], VectorValues.SimilarityFunction.DOT_PRODUCT));
         IllegalArgumentException expected =
             expectThrows(IllegalArgumentException.class, () -> w2.addDocument(doc2));
         assertEquals(
-            "cannot change field \"f\" from vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW "
-                + "to inconsistent vector dimension=1, vector search strategy=DOT_PRODUCT_HNSW",
+            "cannot change field \"f\" from vector dimension=4, vector similarity function=DOT_PRODUCT "
+                + "to inconsistent vector dimension=1, vector similarity function=DOT_PRODUCT",
             expected.getMessage());
       }
     }
   }
 
-  public void testIllegalSearchStrategyChangeTwoWriters() throws Exception {
+  public void testIllegalSimilarityFunctionChangeTwoWriters() throws Exception {
     try (Directory dir = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
 
       try (IndexWriter w2 = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc2 = new Document();
-        doc2.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+        doc2.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.EUCLIDEAN));
         IllegalArgumentException expected =
             expectThrows(IllegalArgumentException.class, () -> w2.addDocument(doc2));
         assertEquals(
-            "cannot change field \"f\" from vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW "
-                + "to inconsistent vector dimension=4, vector search strategy=EUCLIDEAN_HNSW",
+            "cannot change field \"f\" from vector dimension=4, vector similarity function=DOT_PRODUCT "
+                + "to inconsistent vector dimension=4, vector similarity function=EUCLIDEAN",
             expected.getMessage());
       }
     }
@@ -225,7 +225,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
   public void testAddIndexesDirectory0() throws Exception {
     String fieldName = "field";
     Document doc = new Document();
-    doc.add(new VectorField(fieldName, new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+    doc.add(new VectorField(fieldName, new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
     try (Directory dir = newDirectory();
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
@@ -254,7 +254,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         w.addDocument(doc);
       }
       doc.add(
-          new VectorField(fieldName, new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+          new VectorField(fieldName, new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         w2.addDocument(doc);
         w2.addIndexes(dir);
@@ -274,7 +274,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     String fieldName = "field";
     float[] vector = new float[1];
     Document doc = new Document();
-    doc.add(new VectorField(fieldName, vector, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+    doc.add(new VectorField(fieldName, vector, VectorValues.SimilarityFunction.DOT_PRODUCT));
     try (Directory dir = newDirectory();
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
@@ -305,41 +305,41 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[5], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[5], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w2.addDocument(doc);
         IllegalArgumentException expected =
             expectThrows(
                 IllegalArgumentException.class, () -> w2.addIndexes(new Directory[] {dir}));
         assertEquals(
-            "cannot change field \"f\" from vector dimension=5, vector search strategy=DOT_PRODUCT_HNSW "
-                + "to inconsistent vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW",
+            "cannot change field \"f\" from vector dimension=5, vector similarity function=DOT_PRODUCT "
+                + "to inconsistent vector dimension=4, vector similarity function=DOT_PRODUCT",
             expected.getMessage());
       }
     }
   }
 
-  public void testIllegalSearchStrategyChangeViaAddIndexesDirectory() throws Exception {
+  public void testIllegalSimilarityFunctionChangeViaAddIndexesDirectory() throws Exception {
     try (Directory dir = newDirectory();
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.EUCLIDEAN));
         w2.addDocument(doc);
         IllegalArgumentException expected =
             expectThrows(IllegalArgumentException.class, () -> w2.addIndexes(dir));
         assertEquals(
-            "cannot change field \"f\" from vector dimension=4, vector search strategy=EUCLIDEAN_HNSW "
-                + "to inconsistent vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW",
+            "cannot change field \"f\" from vector dimension=4, vector similarity function=EUCLIDEAN "
+                + "to inconsistent vector dimension=4, vector similarity function=DOT_PRODUCT",
             expected.getMessage());
       }
     }
@@ -350,12 +350,12 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[5], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[5], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w2.addDocument(doc);
         try (DirectoryReader r = DirectoryReader.open(dir)) {
           IllegalArgumentException expected =
@@ -363,25 +363,25 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
                   IllegalArgumentException.class,
                   () -> w2.addIndexes(new CodecReader[] {(CodecReader) getOnlyLeafReader(r)}));
           assertEquals(
-              "cannot change field \"f\" from vector dimension=5, vector search strategy=DOT_PRODUCT_HNSW "
-                  + "to inconsistent vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW",
+              "cannot change field \"f\" from vector dimension=5, vector similarity function=DOT_PRODUCT "
+                  + "to inconsistent vector dimension=4, vector similarity function=DOT_PRODUCT",
               expected.getMessage());
         }
       }
     }
   }
 
-  public void testIllegalSearchStrategyChangeViaAddIndexesCodecReader() throws Exception {
+  public void testIllegalSimilarityFunctionChangeViaAddIndexesCodecReader() throws Exception {
     try (Directory dir = newDirectory();
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.EUCLIDEAN));
         w2.addDocument(doc);
         try (DirectoryReader r = DirectoryReader.open(dir)) {
           IllegalArgumentException expected =
@@ -389,8 +389,8 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
                   IllegalArgumentException.class,
                   () -> w2.addIndexes(new CodecReader[] {(CodecReader) getOnlyLeafReader(r)}));
           assertEquals(
-              "cannot change field \"f\" from vector dimension=4, vector search strategy=EUCLIDEAN_HNSW "
-                  + "to inconsistent vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW",
+              "cannot change field \"f\" from vector dimension=4, vector similarity function=EUCLIDEAN "
+                  + "to inconsistent vector dimension=4, vector similarity function=DOT_PRODUCT",
               expected.getMessage());
         }
       }
@@ -402,43 +402,43 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[5], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[5], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w2.addDocument(doc);
         try (DirectoryReader r = DirectoryReader.open(dir)) {
           IllegalArgumentException expected =
               expectThrows(IllegalArgumentException.class, () -> TestUtil.addIndexesSlowly(w2, r));
           assertEquals(
-              "cannot change field \"f\" from vector dimension=5, vector search strategy=DOT_PRODUCT_HNSW "
-                  + "to inconsistent vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW",
+              "cannot change field \"f\" from vector dimension=5, vector similarity function=DOT_PRODUCT "
+                  + "to inconsistent vector dimension=4, vector similarity function=DOT_PRODUCT",
               expected.getMessage());
         }
       }
     }
   }
 
-  public void testIllegalSearchStrategyChangeViaAddIndexesSlowCodecReader() throws Exception {
+  public void testIllegalSimilarityFunctionChangeViaAddIndexesSlowCodecReader() throws Exception {
     try (Directory dir = newDirectory();
         Directory dir2 = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w2 = new IndexWriter(dir2, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.EUCLIDEAN));
         w2.addDocument(doc);
         try (DirectoryReader r = DirectoryReader.open(dir)) {
           IllegalArgumentException expected =
               expectThrows(IllegalArgumentException.class, () -> TestUtil.addIndexesSlowly(w2, r));
           assertEquals(
-              "cannot change field \"f\" from vector dimension=4, vector search strategy=EUCLIDEAN_HNSW "
-                  + "to inconsistent vector dimension=4, vector search strategy=DOT_PRODUCT_HNSW",
+              "cannot change field \"f\" from vector dimension=4, vector similarity function=EUCLIDEAN "
+                  + "to inconsistent vector dimension=4, vector similarity function=DOT_PRODUCT",
               expected.getMessage());
         }
       }
@@ -449,8 +449,8 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory();
         IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc = new Document();
-      doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
-      doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+      doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
+      doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
       IllegalArgumentException expected =
           expectThrows(IllegalArgumentException.class, () -> w.addDocument(doc));
       assertEquals(
@@ -470,10 +470,10 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
                   new VectorField(
                       "f",
                       new float[VectorValues.MAX_DIMENSIONS + 1],
-                      VectorValues.SearchStrategy.DOT_PRODUCT_HNSW)));
+                      VectorValues.SimilarityFunction.DOT_PRODUCT)));
 
       Document doc2 = new Document();
-      doc2.add(new VectorField("f", new float[1], VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+      doc2.add(new VectorField("f", new float[1], VectorValues.SimilarityFunction.EUCLIDEAN));
       w.addDocument(doc2);
     }
   }
@@ -485,11 +485,13 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
       Exception e =
           expectThrows(
               IllegalArgumentException.class,
-              () -> doc.add(new VectorField("f", new float[0], VectorValues.SearchStrategy.NONE)));
+              () ->
+                  doc.add(
+                      new VectorField("f", new float[0], VectorValues.SimilarityFunction.NONE)));
       assertEquals("cannot index an empty vector", e.getMessage());
 
       Document doc2 = new Document();
-      doc2.add(new VectorField("f", new float[1], VectorValues.SearchStrategy.NONE));
+      doc2.add(new VectorField("f", new float[1], VectorValues.SimilarityFunction.NONE));
       w.addDocument(doc2);
     }
   }
@@ -499,14 +501,14 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       IndexWriterConfig iwc = newIndexWriterConfig();
       iwc.setCodec(Codec.forName("SimpleText"));
       try (IndexWriter w = new IndexWriter(dir, iwc)) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
         w.forceMerge(1);
       }
@@ -520,12 +522,12 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, iwc)) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
       }
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("f", new float[4], VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+        doc.add(new VectorField("f", new float[4], VectorValues.SimilarityFunction.DOT_PRODUCT));
         w.addDocument(doc);
         w.forceMerge(1);
       }
@@ -533,7 +535,8 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
   }
 
   public void testInvalidVectorFieldUsage() {
-    VectorField field = new VectorField("field", new float[2], VectorValues.SearchStrategy.NONE);
+    VectorField field =
+        new VectorField("field", new float[2], VectorValues.SimilarityFunction.NONE);
 
     expectThrows(IllegalArgumentException.class, () -> field.setIntValue(14));
 
@@ -548,8 +551,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
       Document doc = new Document();
       doc.add(new StringField("id", "0", Field.Store.NO));
       doc.add(
-          new VectorField(
-              "v", new float[] {2, 3, 5}, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+          new VectorField("v", new float[] {2, 3, 5}, VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
       w.addDocument(new Document());
       w.commit();
@@ -572,14 +574,14 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
       doc.add(new StringField("id", "0", Field.Store.NO));
       doc.add(
           new VectorField(
-              "v0", new float[] {2, 3, 5}, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+              "v0", new float[] {2, 3, 5}, VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
       w.commit();
 
       doc = new Document();
       doc.add(
           new VectorField(
-              "v1", new float[] {2, 3, 5}, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+              "v1", new float[] {2, 3, 5}, VectorValues.SimilarityFunction.DOT_PRODUCT));
       w.addDocument(doc);
       w.forceMerge(1);
     }
@@ -591,13 +593,13 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     int[] fieldDocCounts = new int[numFields];
     float[] fieldTotals = new float[numFields];
     int[] fieldDims = new int[numFields];
-    VectorValues.SearchStrategy[] fieldSearchStrategies =
-        new VectorValues.SearchStrategy[numFields];
+    VectorValues.SimilarityFunction[] fieldSearchStrategies =
+        new VectorValues.SimilarityFunction[numFields];
     for (int i = 0; i < numFields; i++) {
       fieldDims[i] = random().nextInt(20) + 1;
       fieldSearchStrategies[i] =
-          VectorValues.SearchStrategy.values()[
-              random().nextInt(VectorValues.SearchStrategy.values().length)];
+          VectorValues.SimilarityFunction.values()[
+              random().nextInt(VectorValues.SimilarityFunction.values().length)];
     }
     try (Directory dir = newDirectory();
         RandomIndexWriter w = new RandomIndexWriter(random(), dir, newIndexWriterConfig())) {
@@ -644,15 +646,15 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory();
         IndexWriter iw = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc1 = new Document();
-      doc1.add(new VectorField(fieldName, v, VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+      doc1.add(new VectorField(fieldName, v, VectorValues.SimilarityFunction.EUCLIDEAN));
       v[0] = 1;
       Document doc2 = new Document();
-      doc2.add(new VectorField(fieldName, v, VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+      doc2.add(new VectorField(fieldName, v, VectorValues.SimilarityFunction.EUCLIDEAN));
       iw.addDocument(doc1);
       iw.addDocument(doc2);
       v[0] = 2;
       Document doc3 = new Document();
-      doc3.add(new VectorField(fieldName, v, VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
+      doc3.add(new VectorField(fieldName, v, VectorValues.SimilarityFunction.EUCLIDEAN));
       iw.addDocument(doc3);
       iw.forceMerge(1);
       try (IndexReader reader = iw.getReader()) {
@@ -707,15 +709,16 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         IndexWriter iw = new IndexWriter(dir, newIndexWriterConfig())) {
       Document doc = new Document();
       float[] v = new float[] {1};
-      doc.add(new VectorField("field1", v, VectorValues.SearchStrategy.EUCLIDEAN_HNSW));
-      doc.add(new VectorField("field2", new float[] {1, 2, 3}, VectorValues.SearchStrategy.NONE));
+      doc.add(new VectorField("field1", v, VectorValues.SimilarityFunction.EUCLIDEAN));
+      doc.add(
+          new VectorField("field2", new float[] {1, 2, 3}, VectorValues.SimilarityFunction.NONE));
       iw.addDocument(doc);
       v[0] = 2;
       iw.addDocument(doc);
       doc = new Document();
       doc.add(
           new VectorField(
-              "field3", new float[] {1, 2, 3}, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW));
+              "field3", new float[] {1, 2, 3}, VectorValues.SimilarityFunction.DOT_PRODUCT));
       iw.addDocument(doc);
       iw.forceMerge(1);
       try (IndexReader reader = iw.getReader()) {
@@ -776,9 +779,9 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         if (random().nextBoolean() && values[i] != null) {
           // sometimes use a shared scratch array
           System.arraycopy(values[i], 0, scratch, 0, scratch.length);
-          add(iw, fieldName, i, scratch, VectorValues.SearchStrategy.NONE);
+          add(iw, fieldName, i, scratch, VectorValues.SimilarityFunction.NONE);
         } else {
-          add(iw, fieldName, i, values[i], VectorValues.SearchStrategy.NONE);
+          add(iw, fieldName, i, values[i], VectorValues.SimilarityFunction.NONE);
         }
         if (random().nextInt(10) == 2) {
           // sometimes delete a random document
@@ -826,7 +829,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
 
   /**
    * Index random vectors, sometimes skipping documents, sometimes updating a document, sometimes
-   * merging, sometimes sorting the index, using an HNSW search strategy so as to also produce a
+   * merging, sometimes sorting the index, using an HNSW similarity function so as to also produce a
    * graph, and verify that the expected values can be read back consistently.
    */
   public void testRandomWithUpdatesAndGraph() throws Exception {
@@ -851,7 +854,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
         values[i] = value;
         id2value[id] = value;
         id2ord[id] = i;
-        add(iw, fieldName, id, value, VectorValues.SearchStrategy.EUCLIDEAN_HNSW);
+        add(iw, fieldName, id, value, VectorValues.SimilarityFunction.EUCLIDEAN);
       }
       try (IndexReader reader = iw.getReader()) {
         for (LeafReaderContext ctx : reader.leaves()) {
@@ -888,14 +891,14 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
       String field,
       int id,
       float[] vector,
-      VectorValues.SearchStrategy searchStrategy)
+      VectorValues.SimilarityFunction similarityFunction)
       throws IOException {
-    add(iw, field, id, random().nextInt(100), vector, searchStrategy);
+    add(iw, field, id, random().nextInt(100), vector, similarityFunction);
   }
 
   private void add(IndexWriter iw, String field, int id, int sortkey, float[] vector)
       throws IOException {
-    add(iw, field, id, sortkey, vector, VectorValues.SearchStrategy.NONE);
+    add(iw, field, id, sortkey, vector, VectorValues.SimilarityFunction.NONE);
   }
 
   private void add(
@@ -904,11 +907,11 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
       int id,
       int sortkey,
       float[] vector,
-      VectorValues.SearchStrategy searchStrategy)
+      VectorValues.SimilarityFunction similarityFunction)
       throws IOException {
     Document doc = new Document();
     if (vector != null) {
-      doc.add(new VectorField(field, vector, searchStrategy));
+      doc.add(new VectorField(field, vector, similarityFunction));
     }
     doc.add(new NumericDocValuesField("sortkey", sortkey));
     String idString = Integer.toString(id);
@@ -930,10 +933,10 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     try (Directory dir = newDirectory()) {
       try (IndexWriter w = new IndexWriter(dir, newIndexWriterConfig())) {
         Document doc = new Document();
-        doc.add(new VectorField("v1", randomVector(3), VectorValues.SearchStrategy.NONE));
+        doc.add(new VectorField("v1", randomVector(3), VectorValues.SimilarityFunction.NONE));
         w.addDocument(doc);
 
-        doc.add(new VectorField("v2", randomVector(3), VectorValues.SearchStrategy.NONE));
+        doc.add(new VectorField("v2", randomVector(3), VectorValues.SimilarityFunction.NONE));
         w.addDocument(doc);
       }
 
@@ -951,13 +954,13 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
     }
   }
 
-  public void testSearchStrategyIdentifiers() {
-    // make sure we don't accidentally mess up search strategy identifiers by re-ordering their
+  public void testSimilarityFunctionIdentifiers() {
+    // make sure we don't accidentally mess up similarity function identifiers by re-ordering their
     // enumerators
-    assertEquals(0, VectorValues.SearchStrategy.NONE.ordinal());
-    assertEquals(1, VectorValues.SearchStrategy.EUCLIDEAN_HNSW.ordinal());
-    assertEquals(2, VectorValues.SearchStrategy.DOT_PRODUCT_HNSW.ordinal());
-    assertEquals(3, VectorValues.SearchStrategy.values().length);
+    assertEquals(0, VectorValues.SimilarityFunction.NONE.ordinal());
+    assertEquals(1, VectorValues.SimilarityFunction.EUCLIDEAN.ordinal());
+    assertEquals(2, VectorValues.SimilarityFunction.DOT_PRODUCT.ordinal());
+    assertEquals(3, VectorValues.SimilarityFunction.values().length);
   }
 
   public void testAdvance() throws Exception {
@@ -969,7 +972,7 @@ public abstract class BaseVectorFormatTestCase extends BaseIndexFileFormatTestCa
           Document doc = new Document();
           // randomly add a vector field
           if (random().nextInt(4) == 3) {
-            doc.add(new VectorField(fieldName, new float[4], VectorValues.SearchStrategy.NONE));
+            doc.add(new VectorField(fieldName, new float[4], VectorValues.SimilarityFunction.NONE));
           }
           w.addDocument(doc);
         }

lucene/test-framework/src/java/org/apache/lucene/index/MismatchedLeafReader.java

@@ -84,7 +84,7 @@ public class MismatchedLeafReader extends FilterLeafReader {
               oldInfo.getPointNumBytes(), // dimension numBytes
               oldInfo.getVectorDimension(), // number of dimensions of the field's vector
               // distance function for calculating similarity of the field's vector
-              oldInfo.getVectorSearchStrategy(),
+              oldInfo.getVectorSimilarityFunction(),
               oldInfo.isSoftDeletesField()); // used as soft-deletes field
       shuffled.set(i, newInfo);
     }

lucene/test-framework/src/java/org/apache/lucene/index/RandomPostingsTester.java

@@ -140,7 +140,7 @@ public class RandomPostingsTester {
               0,
               0,
               0,
-              VectorValues.SearchStrategy.NONE,
+              VectorValues.SimilarityFunction.NONE,
               false);
       fieldUpto++;
 
@@ -711,7 +711,7 @@ public class RandomPostingsTester {
               0,
               0,
               0,
-              VectorValues.SearchStrategy.NONE,
+              VectorValues.SimilarityFunction.NONE,
               false);
     }