Replace Map<String,Object> with IntObjectHashMap for KnnVectorsReader (#13763)

lucene/CHANGES.txt

@@ -56,6 +56,8 @@ Optimizations
 
 * GITHUB#13958: Speed up advancing within a block. (Adrien Grand)
 
+* GITHUB#13763: Replace Map<String,Object> with IntObjectHashMap for KnnVectorsReader (Pan Guixin)
+
 Bug Fixes
 ---------------------
 * GITHUB#13832: Fixed an issue where the DefaultPassageFormatter.format method did not format passages as intended

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/Lucene90HnswVectorsReader.java

@@ -20,8 +20,6 @@ package org.apache.lucene.backward_codecs.lucene90;
 import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 
 import java.io.IOException;
-import java.util.HashMap;
-import java.util.Map;
 import java.util.SplittableRandom;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.KnnVectorsReader;
@@ -33,6 +31,7 @@ import org.apache.lucene.index.FloatVectorValues;
 import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.search.VectorScorer;
 import org.apache.lucene.store.ChecksumIndexInput;
@@ -50,14 +49,16 @@ import org.apache.lucene.util.hnsw.NeighborQueue;
  */
 public final class Lucene90HnswVectorsReader extends KnnVectorsReader {
 
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorData;
   private final IndexInput vectorIndex;
   private final long checksumSeed;
+  private final FieldInfos fieldInfos;
 
   Lucene90HnswVectorsReader(SegmentReadState state) throws IOException {
     int versionMeta = readMetadata(state);
     long[] checksumRef = new long[1];
+    this.fieldInfos = state.fieldInfos;
     boolean success = false;
     try {
       vectorData =
@@ -158,7 +159,7 @@ public final class Lucene90HnswVectorsReader extends KnnVectorsReader {
 
       FieldEntry fieldEntry = readField(meta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -218,13 +219,18 @@ public final class Lucene90HnswVectorsReader extends KnnVectorsReader {
     CodecUtil.checksumEntireFile(vectorIndex);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    return getOffHeapVectorValues(fieldEntry);
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    return getOffHeapVectorValues(getFieldEntry(field));
   }
 
   @Override
@@ -235,8 +241,7 @@ public final class Lucene90HnswVectorsReader extends KnnVectorsReader {
   @Override
   public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field);
-
     if (fieldEntry.size() == 0) {
       return;
     }

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene91/Lucene91HnswVectorsReader.java

@@ -21,8 +21,6 @@ import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
 import java.util.function.IntUnaryOperator;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.KnnVectorsReader;
@@ -35,6 +33,7 @@ import org.apache.lucene.index.FloatVectorValues;
 import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.search.VectorScorer;
@@ -55,13 +54,15 @@ import org.apache.lucene.util.hnsw.RandomVectorScorer;
  */
 public final class Lucene91HnswVectorsReader extends KnnVectorsReader {
 
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorData;
   private final IndexInput vectorIndex;
   private final DefaultFlatVectorScorer defaultFlatVectorScorer = new DefaultFlatVectorScorer();
+  private final FieldInfos fieldInfos;
 
   Lucene91HnswVectorsReader(SegmentReadState state) throws IOException {
     int versionMeta = readMetadata(state);
+    this.fieldInfos = state.fieldInfos;
     boolean success = false;
     try {
       vectorData =
@@ -154,7 +155,7 @@ public final class Lucene91HnswVectorsReader extends KnnVectorsReader {
       }
       FieldEntry fieldEntry = readField(meta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -214,13 +215,18 @@ public final class Lucene91HnswVectorsReader extends KnnVectorsReader {
     CodecUtil.checksumEntireFile(vectorIndex);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    return getOffHeapVectorValues(fieldEntry);
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    return getOffHeapVectorValues(getFieldEntry(field));
   }
 
   @Override
@@ -231,8 +237,7 @@ public final class Lucene91HnswVectorsReader extends KnnVectorsReader {
   @Override
   public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field);
-
     if (fieldEntry.size() == 0) {
       return;
     }

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene92/Lucene92HnswVectorsReader.java

@@ -21,8 +21,6 @@ import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.KnnVectorsReader;
 import org.apache.lucene.codecs.hnsw.DefaultFlatVectorScorer;
@@ -34,6 +32,7 @@ import org.apache.lucene.index.FloatVectorValues;
 import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.DataInput;
@@ -53,13 +52,15 @@ import org.apache.lucene.util.packed.DirectMonotonicReader;
  */
 public final class Lucene92HnswVectorsReader extends KnnVectorsReader {
 
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorData;
   private final IndexInput vectorIndex;
   private final DefaultFlatVectorScorer defaultFlatVectorScorer = new DefaultFlatVectorScorer();
+  private final FieldInfos fieldInfos;
 
   Lucene92HnswVectorsReader(SegmentReadState state) throws IOException {
     int versionMeta = readMetadata(state);
+    this.fieldInfos = state.fieldInfos;
     boolean success = false;
     try {
       vectorData =
@@ -152,7 +153,7 @@ public final class Lucene92HnswVectorsReader extends KnnVectorsReader {
       }
       FieldEntry fieldEntry = readField(meta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -212,13 +213,18 @@ public final class Lucene92HnswVectorsReader extends KnnVectorsReader {
     CodecUtil.checksumEntireFile(vectorIndex);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    return OffHeapFloatVectorValues.load(fieldEntry, vectorData);
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    return OffHeapFloatVectorValues.load(getFieldEntry(field), vectorData);
   }
 
   @Override
@@ -229,8 +235,7 @@ public final class Lucene92HnswVectorsReader extends KnnVectorsReader {
   @Override
   public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field);
-
     if (fieldEntry.size() == 0) {
       return;
     }

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene94/Lucene94HnswVectorsReader.java

@@ -21,8 +21,6 @@ import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.KnnVectorsReader;
 import org.apache.lucene.codecs.hnsw.DefaultFlatVectorScorer;
@@ -35,6 +33,7 @@ import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorEncoding;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.DataInput;
@@ -54,13 +53,15 @@ import org.apache.lucene.util.packed.DirectMonotonicReader;
  */
 public final class Lucene94HnswVectorsReader extends KnnVectorsReader {
 
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorData;
   private final IndexInput vectorIndex;
   private final DefaultFlatVectorScorer defaultFlatVectorScorer = new DefaultFlatVectorScorer();
+  private final FieldInfos fieldInfos;
 
   Lucene94HnswVectorsReader(SegmentReadState state) throws IOException {
     int versionMeta = readMetadata(state);
+    this.fieldInfos = state.fieldInfos;
     boolean success = false;
     try {
       vectorData =
@@ -153,7 +154,7 @@ public final class Lucene94HnswVectorsReader extends KnnVectorsReader {
       }
       FieldEntry fieldEntry = readField(meta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -230,48 +231,41 @@ public final class Lucene94HnswVectorsReader extends KnnVectorsReader {
     CodecUtil.checksumEntireFile(vectorIndex);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field, VectorEncoding expectedEncoding) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    if (fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
+    if (fieldEntry.vectorEncoding != expectedEncoding) {
       throw new IllegalArgumentException(
           "field=\""
               + field
               + "\" is encoded as: "
               + fieldEntry.vectorEncoding
               + " expected: "
-              + VectorEncoding.FLOAT32);
+              + expectedEncoding);
     }
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
     return OffHeapFloatVectorValues.load(fieldEntry, vectorData);
   }
 
   @Override
   public ByteVectorValues getByteVectorValues(String field) throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
-    if (fieldEntry == null) {
-      throw new IllegalArgumentException("field=\"" + field + "\" not found");
-    }
-    if (fieldEntry.vectorEncoding != VectorEncoding.BYTE) {
-      throw new IllegalArgumentException(
-          "field=\""
-              + field
-              + "\" is encoded as: "
-              + fieldEntry.vectorEncoding
-              + " expected: "
-              + VectorEncoding.BYTE);
-    }
     return OffHeapByteVectorValues.load(fieldEntry, vectorData);
   }
 
   @Override
   public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
-
+    if (fieldEntry.size() == 0 || knnCollector.k() == 0) {
-    if (fieldEntry.size() == 0 || fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
       return;
     }
 
@@ -289,9 +283,8 @@ public final class Lucene94HnswVectorsReader extends KnnVectorsReader {
   @Override
   public void search(String field, byte[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
-
+    if (fieldEntry.size() == 0 || knnCollector.k() == 0) {
-    if (fieldEntry.size() == 0 || fieldEntry.vectorEncoding != VectorEncoding.BYTE) {
       return;
     }
 

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene95/Lucene95HnswVectorsReader.java

@@ -21,8 +21,6 @@ import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.KnnVectorsReader;
 import org.apache.lucene.codecs.hnsw.DefaultFlatVectorScorer;
@@ -39,6 +37,7 @@ import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorEncoding;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.DataInput;
@@ -61,7 +60,7 @@ import org.apache.lucene.util.packed.DirectMonotonicReader;
 public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements HnswGraphProvider {
 
   private final FieldInfos fieldInfos;
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorData;
   private final IndexInput vectorIndex;
   private final DefaultFlatVectorScorer defaultFlatVectorScorer = new DefaultFlatVectorScorer();
@@ -161,7 +160,7 @@ public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements
       }
       FieldEntry fieldEntry = readField(meta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -238,21 +237,27 @@ public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements
     CodecUtil.checksumEntireFile(vectorIndex);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field, VectorEncoding expectedEncoding) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    if (fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
+    if (fieldEntry.vectorEncoding != expectedEncoding) {
       throw new IllegalArgumentException(
           "field=\""
               + field
               + "\" is encoded as: "
               + fieldEntry.vectorEncoding
               + " expected: "
-              + VectorEncoding.FLOAT32);
+              + expectedEncoding);
     }
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
     return OffHeapFloatVectorValues.load(
         fieldEntry.similarityFunction,
         defaultFlatVectorScorer,
@@ -266,19 +271,7 @@ public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements
 
   @Override
   public ByteVectorValues getByteVectorValues(String field) throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
-    if (fieldEntry == null) {
-      throw new IllegalArgumentException("field=\"" + field + "\" not found");
-    }
-    if (fieldEntry.vectorEncoding != VectorEncoding.BYTE) {
-      throw new IllegalArgumentException(
-          "field=\""
-              + field
-              + "\" is encoded as: "
-              + fieldEntry.vectorEncoding
-              + " expected: "
-              + VectorEncoding.BYTE);
-    }
     return OffHeapByteVectorValues.load(
         fieldEntry.similarityFunction,
         defaultFlatVectorScorer,
@@ -293,11 +286,8 @@ public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements
   @Override
   public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
-
+    if (fieldEntry.size() == 0 || knnCollector.k() == 0) {
-    if (fieldEntry.size() == 0
-        || knnCollector.k() == 0
-        || fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
       return;
     }
 
@@ -324,11 +314,8 @@ public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements
   @Override
   public void search(String field, byte[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
-
+    if (fieldEntry.size() == 0 || knnCollector.k() == 0) {
-    if (fieldEntry.size() == 0
-        || knnCollector.k() == 0
-        || fieldEntry.vectorEncoding != VectorEncoding.BYTE) {
       return;
     }
 
@@ -355,12 +342,12 @@ public final class Lucene95HnswVectorsReader extends KnnVectorsReader implements
   /** Get knn graph values; used for testing */
   @Override
   public HnswGraph getGraph(String field) throws IOException {
-    FieldInfo info = fieldInfos.fieldInfo(field);
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    if (info == null) {
+    final FieldEntry entry;
-      throw new IllegalArgumentException("No such field '" + field + "'");
+    if (info == null || (entry = fields.get(info.number)) == null) {
+      throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    FieldEntry entry = fields.get(field);
+    if (entry.vectorIndexLength > 0) {
-    if (entry != null && entry.vectorIndexLength > 0) {
       return getGraph(entry);
     } else {
       return HnswGraph.EMPTY;

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

@@ -26,8 +26,6 @@ import static org.apache.lucene.codecs.simpletext.SimpleTextKnnVectorsWriter.VEC
 
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
-import java.util.HashMap;
-import java.util.Map;
 import org.apache.lucene.codecs.KnnVectorsReader;
 import org.apache.lucene.index.ByteVectorValues;
 import org.apache.lucene.index.CorruptIndexException;
@@ -36,6 +34,7 @@ import org.apache.lucene.index.FloatVectorValues;
 import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.search.VectorScorer;
@@ -63,7 +62,7 @@ public class SimpleTextKnnVectorsReader extends KnnVectorsReader {
   private final SegmentReadState readState;
   private final IndexInput dataIn;
   private final BytesRefBuilder scratch = new BytesRefBuilder();
-  private final Map<String, FieldEntry> fieldEntries = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fieldEntries = new IntObjectHashMap<>();
 
   SimpleTextKnnVectorsReader(SegmentReadState readState) throws IOException {
     this.readState = readState;
@@ -91,9 +90,9 @@ public class SimpleTextKnnVectorsReader extends KnnVectorsReader {
         for (int i = 0; i < size; i++) {
           docIds[i] = readInt(in, EMPTY);
         }
-        assert fieldEntries.containsKey(fieldName) == false;
+        assert fieldEntries.containsKey(fieldNumber) == false;
         fieldEntries.put(
-            fieldName,
+            fieldNumber,
             new FieldEntry(
                 dimension,
                 vectorDataOffset,
@@ -126,7 +125,7 @@ public class SimpleTextKnnVectorsReader extends KnnVectorsReader {
       throw new IllegalStateException(
           "KNN vectors readers should not be called on fields that don't enable KNN vectors");
     }
-    FieldEntry fieldEntry = fieldEntries.get(field);
+    FieldEntry fieldEntry = fieldEntries.get(info.number);
     if (fieldEntry == null) {
       // mirror the handling in Lucene90VectorReader#getVectorValues
       // needed to pass TestSimpleTextKnnVectorsFormat#testDeleteAllVectorDocs
@@ -159,7 +158,7 @@ public class SimpleTextKnnVectorsReader extends KnnVectorsReader {
       throw new IllegalStateException(
           "KNN vectors readers should not be called on fields that don't enable KNN vectors");
     }
-    FieldEntry fieldEntry = fieldEntries.get(field);
+    FieldEntry fieldEntry = fieldEntries.get(info.number);
     if (fieldEntry == null) {
       // mirror the handling in Lucene90VectorReader#getVectorValues
       // needed to pass TestSimpleTextKnnVectorsFormat#testDeleteAllVectorDocs

lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99FlatVectorsReader.java

@@ -21,8 +21,6 @@ import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsReader.readSi
 import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsReader.readVectorEncoding;
 
 import java.io.IOException;
-import java.util.HashMap;
-import java.util.Map;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.hnsw.FlatVectorsReader;
 import org.apache.lucene.codecs.hnsw.FlatVectorsScorer;
@@ -38,6 +36,7 @@ import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorEncoding;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.IOContext;
 import org.apache.lucene.store.IndexInput;
@@ -56,13 +55,15 @@ public final class Lucene99FlatVectorsReader extends FlatVectorsReader {
   private static final long SHALLOW_SIZE =
       RamUsageEstimator.shallowSizeOfInstance(Lucene99FlatVectorsFormat.class);
 
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorData;
+  private final FieldInfos fieldInfos;
 
   public Lucene99FlatVectorsReader(SegmentReadState state, FlatVectorsScorer scorer)
       throws IOException {
     super(scorer);
     int versionMeta = readMetadata(state);
+    this.fieldInfos = state.fieldInfos;
     boolean success = false;
     try {
       vectorData =
@@ -155,15 +156,13 @@ public final class Lucene99FlatVectorsReader extends FlatVectorsReader {
         throw new CorruptIndexException("Invalid field number: " + fieldNumber, meta);
       }
       FieldEntry fieldEntry = FieldEntry.create(meta, info);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
   @Override
   public long ramBytesUsed() {
-    return Lucene99FlatVectorsReader.SHALLOW_SIZE
+    return Lucene99FlatVectorsReader.SHALLOW_SIZE + fields.ramBytesUsed();
-        + RamUsageEstimator.sizeOfMap(
-            fields, RamUsageEstimator.shallowSizeOfInstance(FieldEntry.class));
   }
 
   @Override
@@ -171,21 +170,27 @@ public final class Lucene99FlatVectorsReader extends FlatVectorsReader {
     CodecUtil.checksumEntireFile(vectorData);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field, VectorEncoding expectedEncoding) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    if (fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
+    if (fieldEntry.vectorEncoding != expectedEncoding) {
       throw new IllegalArgumentException(
           "field=\""
               + field
               + "\" is encoded as: "
               + fieldEntry.vectorEncoding
               + " expected: "
-              + VectorEncoding.FLOAT32);
+              + expectedEncoding);
     }
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
     return OffHeapFloatVectorValues.load(
         fieldEntry.similarityFunction,
         vectorScorer,
@@ -199,19 +204,7 @@ public final class Lucene99FlatVectorsReader extends FlatVectorsReader {
 
   @Override
   public ByteVectorValues getByteVectorValues(String field) throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
-    if (fieldEntry == null) {
-      throw new IllegalArgumentException("field=\"" + field + "\" not found");
-    }
-    if (fieldEntry.vectorEncoding != VectorEncoding.BYTE) {
-      throw new IllegalArgumentException(
-          "field=\""
-              + field
-              + "\" is encoded as: "
-              + fieldEntry.vectorEncoding
-              + " expected: "
-              + VectorEncoding.BYTE);
-    }
     return OffHeapByteVectorValues.load(
         fieldEntry.similarityFunction,
         vectorScorer,
@@ -225,10 +218,7 @@ public final class Lucene99FlatVectorsReader extends FlatVectorsReader {
 
   @Override
   public RandomVectorScorer getRandomVectorScorer(String field, float[] target) throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
-    if (fieldEntry == null || fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
-      return null;
-    }
     return vectorScorer.getRandomVectorScorer(
         fieldEntry.similarityFunction,
         OffHeapFloatVectorValues.load(
@@ -245,10 +235,7 @@ public final class Lucene99FlatVectorsReader extends FlatVectorsReader {
 
   @Override
   public RandomVectorScorer getRandomVectorScorer(String field, byte[] target) throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
-    if (fieldEntry == null || fieldEntry.vectorEncoding != VectorEncoding.BYTE) {
-      return null;
-    }
     return vectorScorer.getRandomVectorScorer(
         fieldEntry.similarityFunction,
         OffHeapByteVectorValues.load(

lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99HnswVectorsReader.java

@@ -21,9 +21,7 @@ import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.KnnVectorsReader;
 import org.apache.lucene.codecs.hnsw.FlatVectorsReader;
@@ -37,6 +35,7 @@ import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorEncoding;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.DataInput;
@@ -70,7 +69,7 @@ public final class Lucene99HnswVectorsReader extends KnnVectorsReader
 
   private final FlatVectorsReader flatVectorsReader;
   private final FieldInfos fieldInfos;
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput vectorIndex;
 
   public Lucene99HnswVectorsReader(SegmentReadState state, FlatVectorsReader flatVectorsReader)
@@ -162,7 +161,7 @@ public final class Lucene99HnswVectorsReader extends KnnVectorsReader
       }
       FieldEntry fieldEntry = readField(meta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -225,8 +224,7 @@ public final class Lucene99HnswVectorsReader extends KnnVectorsReader
   @Override
   public long ramBytesUsed() {
     return Lucene99HnswVectorsReader.SHALLOW_SIZE
-        + RamUsageEstimator.sizeOfMap(
+        + fields.ramBytesUsed()
-            fields, RamUsageEstimator.shallowSizeOfInstance(FieldEntry.class))
         + flatVectorsReader.ramBytesUsed();
   }
 
@@ -246,25 +244,43 @@ public final class Lucene99HnswVectorsReader extends KnnVectorsReader
     return flatVectorsReader.getByteVectorValues(field);
   }
 
+  private FieldEntry getFieldEntry(String field, VectorEncoding expectedEncoding) {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
+    final FieldEntry fieldEntry;
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
+      throw new IllegalArgumentException("field=\"" + field + "\" not found");
+    }
+    if (fieldEntry.vectorEncoding != expectedEncoding) {
+      throw new IllegalArgumentException(
+          "field=\""
+              + field
+              + "\" is encoded as: "
+              + fieldEntry.vectorEncoding
+              + " expected: "
+              + expectedEncoding);
+    }
+    return fieldEntry;
+  }
+
   @Override
   public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.FLOAT32);
     search(
-        fields.get(field),
+        fieldEntry,
         knnCollector,
         acceptDocs,
-        VectorEncoding.FLOAT32,
         () -> flatVectorsReader.getRandomVectorScorer(field, target));
   }
 
   @Override
   public void search(String field, byte[] target, KnnCollector knnCollector, Bits acceptDocs)
       throws IOException {
+    final FieldEntry fieldEntry = getFieldEntry(field, VectorEncoding.BYTE);
     search(
-        fields.get(field),
+        fieldEntry,
         knnCollector,
         acceptDocs,
-        VectorEncoding.BYTE,
         () -> flatVectorsReader.getRandomVectorScorer(field, target));
   }
 
@@ -272,13 +288,10 @@ public final class Lucene99HnswVectorsReader extends KnnVectorsReader
       FieldEntry fieldEntry,
       KnnCollector knnCollector,
       Bits acceptDocs,
-      VectorEncoding vectorEncoding,
       IOSupplier<RandomVectorScorer> scorerSupplier)
       throws IOException {
 
-    if (fieldEntry.size() == 0
+    if (fieldEntry.size() == 0 || knnCollector.k() == 0) {
-        || knnCollector.k() == 0
-        || fieldEntry.vectorEncoding != vectorEncoding) {
       return;
     }
     final RandomVectorScorer scorer = scorerSupplier.get();
@@ -304,12 +317,12 @@ public final class Lucene99HnswVectorsReader extends KnnVectorsReader
 
   @Override
   public HnswGraph getGraph(String field) throws IOException {
-    FieldInfo info = fieldInfos.fieldInfo(field);
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    if (info == null) {
+    final FieldEntry entry;
-      throw new IllegalArgumentException("No such field '" + field + "'");
+    if (info == null || (entry = fields.get(info.number)) == null) {
+      throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
-    FieldEntry entry = fields.get(field);
+    if (entry.vectorIndexLength > 0) {
-    if (entry != null && entry.vectorIndexLength > 0) {
       return getGraph(entry);
     } else {
       return HnswGraph.EMPTY;

lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99ScalarQuantizedVectorsReader.java

@@ -21,8 +21,6 @@ import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsReader.readSi
 import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsReader.readVectorEncoding;
 
 import java.io.IOException;
-import java.util.HashMap;
-import java.util.Map;
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.hnsw.FlatVectorsReader;
 import org.apache.lucene.codecs.hnsw.FlatVectorsScorer;
@@ -36,6 +34,7 @@ import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.VectorEncoding;
 import org.apache.lucene.index.VectorSimilarityFunction;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
 import org.apache.lucene.search.VectorScorer;
 import org.apache.lucene.store.ChecksumIndexInput;
 import org.apache.lucene.store.IOContext;
@@ -59,15 +58,17 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
   private static final long SHALLOW_SIZE =
       RamUsageEstimator.shallowSizeOfInstance(Lucene99ScalarQuantizedVectorsReader.class);
 
-  private final Map<String, FieldEntry> fields = new HashMap<>();
+  private final IntObjectHashMap<FieldEntry> fields = new IntObjectHashMap<>();
   private final IndexInput quantizedVectorData;
   private final FlatVectorsReader rawVectorsReader;
+  private final FieldInfos fieldInfos;
 
   public Lucene99ScalarQuantizedVectorsReader(
       SegmentReadState state, FlatVectorsReader rawVectorsReader, FlatVectorsScorer scorer)
       throws IOException {
     super(scorer);
     this.rawVectorsReader = rawVectorsReader;
+    this.fieldInfos = state.fieldInfos;
     int versionMeta = -1;
     String metaFileName =
         IndexFileNames.segmentFileName(
@@ -118,7 +119,7 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
       }
       FieldEntry fieldEntry = readField(meta, versionMeta, info);
       validateFieldEntry(info, fieldEntry);
-      fields.put(info.name, fieldEntry);
+      fields.put(info.number, fieldEntry);
     }
   }
 
@@ -163,10 +164,10 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
     CodecUtil.checksumEntireFile(quantizedVectorData);
   }
 
-  @Override
+  private FieldEntry getFieldEntry(String field) {
-  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldInfo info = fieldInfos.fieldInfo(field);
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry;
-    if (fieldEntry == null) {
+    if (info == null || (fieldEntry = fields.get(info.number)) == null) {
       throw new IllegalArgumentException("field=\"" + field + "\" not found");
     }
     if (fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
@@ -178,6 +179,12 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
               + " expected: "
               + VectorEncoding.FLOAT32);
     }
+    return fieldEntry;
+  }
+
+  @Override
+  public FloatVectorValues getFloatVectorValues(String field) throws IOException {
+    final FieldEntry fieldEntry = getFieldEntry(field);
     final FloatVectorValues rawVectorValues = rawVectorsReader.getFloatVectorValues(field);
     OffHeapQuantizedByteVectorValues quantizedByteVectorValues =
         OffHeapQuantizedByteVectorValues.load(
@@ -241,10 +248,7 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
 
   @Override
   public RandomVectorScorer getRandomVectorScorer(String field, float[] target) throws IOException {
-    FieldEntry fieldEntry = fields.get(field);
+    final FieldEntry fieldEntry = getFieldEntry(field);
-    if (fieldEntry == null || fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
-      return null;
-    }
     if (fieldEntry.scalarQuantizer == null) {
       return rawVectorsReader.getRandomVectorScorer(field, target);
     }
@@ -275,12 +279,7 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
 
   @Override
   public long ramBytesUsed() {
-    long size = SHALLOW_SIZE;
+    return SHALLOW_SIZE + fields.ramBytesUsed() + rawVectorsReader.ramBytesUsed();
-    size +=
-        RamUsageEstimator.sizeOfMap(
-            fields, RamUsageEstimator.shallowSizeOfInstance(FieldEntry.class));
-    size += rawVectorsReader.ramBytesUsed();
-    return size;
   }
 
   private FieldEntry readField(IndexInput input, int versionMeta, FieldInfo info)
@@ -301,11 +300,8 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
   }
 
   @Override
-  public QuantizedByteVectorValues getQuantizedVectorValues(String fieldName) throws IOException {
+  public QuantizedByteVectorValues getQuantizedVectorValues(String field) throws IOException {
-    FieldEntry fieldEntry = fields.get(fieldName);
+    final FieldEntry fieldEntry = getFieldEntry(field);
-    if (fieldEntry == null || fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
-      return null;
-    }
     return OffHeapQuantizedByteVectorValues.load(
         fieldEntry.ordToDoc,
         fieldEntry.dimension,
@@ -320,11 +316,8 @@ public final class Lucene99ScalarQuantizedVectorsReader extends FlatVectorsReade
   }
 
   @Override
-  public ScalarQuantizer getQuantizationState(String fieldName) {
+  public ScalarQuantizer getQuantizationState(String field) {
-    FieldEntry fieldEntry = fields.get(fieldName);
+    final FieldEntry fieldEntry = getFieldEntry(field);
-    if (fieldEntry == null || fieldEntry.vectorEncoding != VectorEncoding.FLOAT32) {
-      return null;
-    }
     return fieldEntry.scalarQuantizer;
   }
 

lucene/core/src/java/org/apache/lucene/codecs/perfield/PerFieldKnnVectorsFormat.java

@@ -19,7 +19,9 @@ package org.apache.lucene.codecs.perfield;
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.ServiceLoader;
 import org.apache.lucene.codecs.KnnFieldVectorsWriter;
@@ -28,11 +30,14 @@ import org.apache.lucene.codecs.KnnVectorsReader;
 import org.apache.lucene.codecs.KnnVectorsWriter;
 import org.apache.lucene.index.ByteVectorValues;
 import org.apache.lucene.index.FieldInfo;
+import org.apache.lucene.index.FieldInfos;
 import org.apache.lucene.index.FloatVectorValues;
 import org.apache.lucene.index.MergeState;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.SegmentWriteState;
 import org.apache.lucene.index.Sorter;
+import org.apache.lucene.internal.hppc.IntObjectHashMap;
+import org.apache.lucene.internal.hppc.ObjectCursor;
 import org.apache.lucene.search.KnnCollector;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.IOUtils;
@@ -186,7 +191,8 @@ public abstract class PerFieldKnnVectorsFormat extends KnnVectorsFormat {
   /** VectorReader that can wrap multiple delegate readers, selected by field. */
   public static class FieldsReader extends KnnVectorsReader {
 
-    private final Map<String, KnnVectorsReader> fields = new HashMap<>();
+    private final IntObjectHashMap<KnnVectorsReader> fields = new IntObjectHashMap<>();
+    private final FieldInfos fieldInfos;
 
     /**
      * Create a FieldsReader over a segment, opening VectorReaders for each KnnVectorsFormat
@@ -196,7 +202,7 @@ public abstract class PerFieldKnnVectorsFormat extends KnnVectorsFormat {
      * @throws IOException if one of the delegate readers throws
      */
     public FieldsReader(final SegmentReadState readState) throws IOException {
-
+      this.fieldInfos = readState.fieldInfos;
       // Init each unique format:
       boolean success = false;
       Map<String, KnnVectorsReader> formats = new HashMap<>();
@@ -221,7 +227,7 @@ public abstract class PerFieldKnnVectorsFormat extends KnnVectorsFormat {
                     segmentSuffix,
                     format.fieldsReader(new SegmentReadState(readState, segmentSuffix)));
               }
-              fields.put(fieldName, formats.get(segmentSuffix));
+              fields.put(fi.number, formats.get(segmentSuffix));
             }
           }
         }
@@ -239,51 +245,69 @@ public abstract class PerFieldKnnVectorsFormat extends KnnVectorsFormat {
      * @param field the name of a numeric vector field
      */
     public KnnVectorsReader getFieldReader(String field) {
-      return fields.get(field);
+      final FieldInfo info = fieldInfos.fieldInfo(field);
+      if (info == null) {
+        return null;
+      }
+      return fields.get(info.number);
     }
 
     @Override
     public void checkIntegrity() throws IOException {
-      for (KnnVectorsReader reader : fields.values()) {
+      for (ObjectCursor<KnnVectorsReader> cursor : fields.values()) {
-        reader.checkIntegrity();
+        cursor.value.checkIntegrity();
       }
     }
 
     @Override
     public FloatVectorValues getFloatVectorValues(String field) throws IOException {
-      KnnVectorsReader knnVectorsReader = fields.get(field);
+      final FieldInfo info = fieldInfos.fieldInfo(field);
-      if (knnVectorsReader == null) {
+      final KnnVectorsReader reader;
+      if (info == null || (reader = fields.get(info.number)) == null) {
         return null;
-      } else {
-        return knnVectorsReader.getFloatVectorValues(field);
       }
+      return reader.getFloatVectorValues(field);
     }
 
     @Override
     public ByteVectorValues getByteVectorValues(String field) throws IOException {
-      KnnVectorsReader knnVectorsReader = fields.get(field);
+      final FieldInfo info = fieldInfos.fieldInfo(field);
-      if (knnVectorsReader == null) {
+      final KnnVectorsReader reader;
+      if (info == null || (reader = fields.get(info.number)) == null) {
         return null;
-      } else {
-        return knnVectorsReader.getByteVectorValues(field);
       }
+      return reader.getByteVectorValues(field);
     }
 
     @Override
     public void search(String field, float[] target, KnnCollector knnCollector, Bits acceptDocs)
         throws IOException {
-      fields.get(field).search(field, target, knnCollector, acceptDocs);
+      final FieldInfo info = fieldInfos.fieldInfo(field);
+      final KnnVectorsReader reader;
+      if (info == null || (reader = fields.get(info.number)) == null) {
+        return;
+      }
+      reader.search(field, target, knnCollector, acceptDocs);
     }
 
     @Override
     public void search(String field, byte[] target, KnnCollector knnCollector, Bits acceptDocs)
         throws IOException {
-      fields.get(field).search(field, target, knnCollector, acceptDocs);
+      final FieldInfo info = fieldInfos.fieldInfo(field);
+      final KnnVectorsReader reader;
+      if (info == null || (reader = fields.get(info.number)) == null) {
+        return;
+      }
+      reader.search(field, target, knnCollector, acceptDocs);
     }
 
     @Override
     public void close() throws IOException {
-      IOUtils.close(fields.values());
+      List<KnnVectorsReader> readers = new ArrayList<>(fields.size());
+      for (ObjectCursor<KnnVectorsReader> cursor : fields.values()) {
+        readers.add(cursor.value);
+      }
+      IOUtils.close(readers);
     }
   }