Introduce index.mapping.use_binary_doc_values to experiment with binary doc values for keyword field.

Author: martijnvg

benchmarks/src/main/java/org/elasticsearch/benchmark/_nightly/esql/ValuesSourceReaderBenchmark.java

@@ -222,8 +222,8 @@ private static BlockLoader blockLoader(String name) {
                 Lucene.KEYWORD_ANALYZER,
                 Lucene.KEYWORD_ANALYZER,
                 new KeywordFieldMapper.Builder(name, IndexVersion.current()).docValues(ft.docValuesType() != DocValuesType.NONE),
-                syntheticSource
-            ).blockLoader(new MappedFieldType.BlockLoaderContext() {
+                syntheticSource,
+                    useBinaryDocValues).blockLoader(new MappedFieldType.BlockLoaderContext() {
                 @Override
                 public String indexName() {
                     return "benchmark";

modules/mapper-extras/src/test/java/org/elasticsearch/index/mapper/extras/MatchOnlyTextFieldTypeTests.java

@@ -298,8 +298,8 @@ public void testBlockLoaderDoesNotUseSyntheticSourceDelegateWhenIgnoreAboveIsSet
             mock(NamedAnalyzer.class),
             mock(NamedAnalyzer.class),
             builder,
-            true
-        );
+            true,
+                useBinaryDocValues);
 
         MatchOnlyTextFieldMapper.MatchOnlyTextFieldType ft = new MatchOnlyTextFieldMapper.MatchOnlyTextFieldType(
             "parent",
@@ -346,8 +346,8 @@ public void testBlockLoaderDoesNotUseSyntheticSourceDelegateWhenIgnoreAboveIsSet
             mock(NamedAnalyzer.class),
             mock(NamedAnalyzer.class),
             builder,
-            true
-        );
+            true,
+                useBinaryDocValues);
 
         MatchOnlyTextFieldMapper.MatchOnlyTextFieldType ft = new MatchOnlyTextFieldMapper.MatchOnlyTextFieldType(
             "parent",

server/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java

@@ -243,6 +243,7 @@ public final class IndexScopedSettings extends AbstractScopedSettings {
         if (IndexSettings.DOC_VALUES_SKIPPER) {
             settings.add(IndexSettings.USE_DOC_VALUES_SKIPPER);
         }
+        settings.add(IndexSettings.USE_BINARY_DOC_VALUES);
         settings.add(IndexSettings.INDEX_MAPPING_EXCLUDE_SOURCE_VECTORS_SETTING);
         BUILT_IN_INDEX_SETTINGS = Collections.unmodifiableSet(settings);
     };

server/src/main/java/org/elasticsearch/index/IndexSettings.java

@@ -675,6 +675,13 @@ public boolean isES87TSDBCodecEnabled() {
         Property.Final
     );
 
+    public static final Setting<Boolean> USE_BINARY_DOC_VALUES = Setting.boolSetting(
+        "index.mapping.use_binary_doc_values",
+        false,
+        Property.IndexScope,
+        Property.Final
+    );
+
     /**
      * The {@link IndexMode "mode"} of the index.
      */

server/src/main/java/org/elasticsearch/index/mapper/BlockDocValuesReader.java

@@ -925,6 +925,28 @@ public AllReader reader(LeafReaderContext context) throws IOException {
         }
     }
 
+    public static class BytesRefsFromBinaryBlockLoader extends DocValuesBlockLoader {
+        private final String fieldName;
+
+        public BytesRefsFromBinaryBlockLoader(String fieldName) {
+            this.fieldName = fieldName;
+        }
+
+        @Override
+        public Builder builder(BlockFactory factory, int expectedCount) {
+            return factory.bytesRefs(expectedCount);
+        }
+
+        @Override
+        public AllReader reader(LeafReaderContext context) throws IOException {
+            BinaryDocValues docValues = context.reader().getBinaryDocValues(fieldName);
+            if (docValues == null) {
+                return new ConstantNullsReader();
+            }
+            return new BytesRefsFromBinary(docValues);
+        }
+    }
+
     abstract static class AbstractBytesRefsFromBinary extends BlockDocValuesReader {
         protected final BinaryDocValues docValues;