Replace SourceLookup with SourceProvider interface (#91540)

SourceLookup mixes up several concerns - lazy loading, map access to scripts,
different access providers - and duplicates logic (such as that choosing how to
apply filtering) that is better handled directly in the Source interface.

This commit removes SourceLookup entirely and replaces it with a new
SourceProvider interface, with a simple stored fields reader implementation.
SearchLookup implements this interface directly, and the fetch phase uses
a custom implementation to provide its separately loaded source to fetch-time
scripts.

benchmarks/src/main/java/org/elasticsearch/benchmark/script/ScriptScoreBenchmark.java

@@ -40,7 +40,7 @@ import org.elasticsearch.script.DocValuesDocReader;
 import org.elasticsearch.script.ScoreScript;
 import org.elasticsearch.script.ScriptModule;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
 import org.openjdk.jmh.annotations.Fork;
@@ -90,7 +90,7 @@ public class ScriptScoreBenchmark {
     private final SearchLookup lookup = new SearchLookup(
         fieldTypes::get,
         (mft, lookup, fdo) -> mft.fielddataBuilder(FieldDataContext.noRuntimeFields("benchmark")).build(fieldDataCache, breakerService),
-        new SourceLookup.ReaderSourceProvider()
+        SourceProvider.fromStoredFields()
     );
 
     @Param({ "expression", "metal", "painless_cast", "painless_def" })

modules/lang-expression/src/test/java/org/elasticsearch/script/expression/ExpressionFieldScriptTests.java

@@ -15,8 +15,9 @@ import org.elasticsearch.index.mapper.NumberFieldMapper;
 import org.elasticsearch.script.FieldScript;
 import org.elasticsearch.script.ScriptException;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.text.ParseException;
@@ -53,7 +54,7 @@ public class ExpressionFieldScriptTests extends ESTestCase {
         lookup = new SearchLookup(
             field -> field.equals("field") ? fieldType : null,
             (ignored, _lookup, fdt) -> fieldData,
-            new SourceLookup.ReaderSourceProvider()
+            (ctx, doc) -> Source.empty(XContentType.JSON)
         );
     }
 

modules/lang-expression/src/test/java/org/elasticsearch/script/expression/ExpressionNumberSortScriptTests.java

@@ -17,8 +17,9 @@ import org.elasticsearch.script.DocValuesDocReader;
 import org.elasticsearch.script.NumberSortScript;
 import org.elasticsearch.script.ScriptException;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.text.ParseException;
@@ -54,7 +55,7 @@ public class ExpressionNumberSortScriptTests extends ESTestCase {
         lookup = new SearchLookup(
             field -> field.equals("field") ? fieldType : null,
             (ignored, _lookup, fdt) -> fieldData,
-            new SourceLookup.ReaderSourceProvider()
+            (ctx, doc) -> Source.empty(XContentType.JSON)
         );
     }
 

modules/lang-expression/src/test/java/org/elasticsearch/script/expression/ExpressionTermsSetQueryTests.java

@@ -16,8 +16,9 @@ import org.elasticsearch.index.mapper.NumberFieldMapper.NumberType;
 import org.elasticsearch.script.ScriptException;
 import org.elasticsearch.script.TermsSetQueryScript;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.text.ParseException;
@@ -53,7 +54,7 @@ public class ExpressionTermsSetQueryTests extends ESTestCase {
         lookup = new SearchLookup(
             field -> field.equals("field") ? fieldType : null,
             (ignored, _lookup, fdt) -> fieldData,
-            new SourceLookup.ReaderSourceProvider()
+            (ctx, doc) -> Source.empty(XContentType.JSON)
         );
     }
 

modules/lang-painless/src/test/java/org/elasticsearch/painless/ScriptedMetricAggContextsTests.java

@@ -16,7 +16,8 @@ import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.script.ScriptedMetricAggContexts;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -24,6 +25,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Supplier;
 
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -110,9 +112,8 @@ public class ScriptedMetricAggContextsTests extends ScriptTestCase {
         SearchLookup lookup = mock(SearchLookup.class);
         LeafSearchLookup leafLookup = mock(LeafSearchLookup.class);
         when(lookup.getLeafSearchLookup(leafReaderContext)).thenReturn(leafLookup);
-        SourceLookup sourceLookup = mock(SourceLookup.class);
-        when(leafLookup.asMap()).thenReturn(Collections.singletonMap("_source", sourceLookup));
-        when(sourceLookup.source()).thenReturn(Collections.singletonMap("test", 1));
+        Supplier<Source> source = () -> Source.fromMap(Map.of("test", 1), XContentType.JSON);
+        when(leafLookup.asMap()).thenReturn(Collections.singletonMap("_source", source));
         ScriptedMetricAggContexts.MapScript.LeafFactory leafFactory = factory.newFactory(params, state, lookup);
         ScriptedMetricAggContexts.MapScript script = leafFactory.newInstance(leafReaderContext);
 
@@ -141,9 +142,8 @@ public class ScriptedMetricAggContextsTests extends ScriptTestCase {
         SearchLookup lookup = mock(SearchLookup.class);
         LeafSearchLookup leafLookup = mock(LeafSearchLookup.class);
         when(lookup.getLeafSearchLookup(leafReaderContext)).thenReturn(leafLookup);
-        SourceLookup sourceLookup = mock(SourceLookup.class);
-        when(leafLookup.asMap()).thenReturn(Collections.singletonMap("_source", sourceLookup));
-        when(sourceLookup.source()).thenReturn(Collections.singletonMap("three", 3));
+        Supplier<Source> source = () -> Source.fromMap(Map.of("three", 3), XContentType.JSON);
+        when(leafLookup.asMap()).thenReturn(Collections.singletonMap("_source", source));
         ScriptedMetricAggContexts.MapScript.LeafFactory leafFactory = factory.newFactory(params, state, lookup);
         ScriptedMetricAggContexts.MapScript script = leafFactory.newInstance(leafReaderContext);
 

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/MatchOnlyTextFieldMapper.java

@@ -53,7 +53,7 @@ import org.elasticsearch.index.mapper.ValueFetcher;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.script.field.TextDocValuesField;
 import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -211,14 +211,13 @@ public class MatchOnlyTextFieldMapper extends FieldMapper {
                     };
                 };
             }
-            SourceLookup sourceLookup = searchExecutionContext.lookup().source();
             ValueFetcher valueFetcher = valueFetcher(searchExecutionContext, null);
+            SourceProvider sourceProvider = searchExecutionContext.lookup();
             return context -> {
                 valueFetcher.setNextReader(context);
                 return docID -> {
                     try {
-                        sourceLookup.setSegmentAndDocument(context, docID);
-                        return valueFetcher.fetchValues(sourceLookup, docID, new ArrayList<>());
+                        return valueFetcher.fetchValues(sourceProvider.getSource(context, docID), docID, new ArrayList<>());
                     } catch (IOException e) {
                         throw new UncheckedIOException(e);
                     }
@@ -338,7 +337,7 @@ public class MatchOnlyTextFieldMapper extends FieldMapper {
                 name(),
                 CoreValuesSourceType.KEYWORD,
                 SourceValueFetcher.toString(fieldDataContext.sourcePathsLookup().apply(name())),
-                fieldDataContext.lookupSupplier().get().source(),
+                fieldDataContext.lookupSupplier().get(),
                 TextDocValuesField::new
             );
         }

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/ScaledFloatFieldMapper.java

@@ -310,7 +310,7 @@ public class ScaledFloatFieldMapper extends FieldMapper {
                     name(),
                     valuesSourceType,
                     sourceValueFetcher(sourcePaths),
-                    searchLookup.source(),
+                    searchLookup,
                     ScaledFloatDocValuesField::new
                 );
             }

server/src/internalClusterTest/java/org/elasticsearch/search/fields/SearchFieldsIT.java

@@ -28,7 +28,7 @@ import org.elasticsearch.script.ScriptType;
 import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
 import org.elasticsearch.search.lookup.FieldLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.search.sort.SortOrder;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.test.InternalSettingsPlugin;
@@ -53,6 +53,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 import static java.util.Collections.singleton;
 import static org.elasticsearch.action.support.WriteRequest.RefreshPolicy.IMMEDIATE;
@@ -142,7 +143,7 @@ public class SearchFieldsIT extends ESIntegTestCase {
 
         static Object sourceScript(Map<String, Object> vars, String path) {
             @SuppressWarnings("unchecked")
-            Map<String, Object> source = ((SourceLookup) vars.get("_source")).source();
+            Map<String, Object> source = ((Supplier<Source>) vars.get("_source")).get().source();
             return XContentMapValues.extractValue(path, source);
         }
 

server/src/internalClusterTest/java/org/elasticsearch/search/stats/SearchStatsIT.java

@@ -25,7 +25,7 @@ import org.elasticsearch.script.MockScriptPlugin;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptType;
 import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.test.ESIntegTestCase;
 
 import java.util.Collection;
@@ -34,6 +34,7 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 import static org.elasticsearch.cluster.metadata.IndexMetadata.SETTING_NUMBER_OF_REPLICAS;
 import static org.elasticsearch.cluster.metadata.IndexMetadata.SETTING_NUMBER_OF_SHARDS;
@@ -60,9 +61,10 @@ public class SearchStatsIT extends ESIntegTestCase {
     public static class CustomScriptPlugin extends MockScriptPlugin {
 
         @Override
+        @SuppressWarnings("unchecked")
         protected Map<String, Function<Map<String, Object>, Object>> pluginScripts() {
             return Collections.singletonMap("_source.field", vars -> {
-                Map<?, ?> src = ((SourceLookup) vars.get("_source")).source();
+                Map<?, ?> src = ((Supplier<Source>) vars.get("_source")).get().source();
                 return src.get("field");
             });
         }

server/src/main/java/org/elasticsearch/index/fielddata/SourceValueFetcherIndexFieldData.java

@@ -17,7 +17,7 @@ import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.MultiValueMode;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.search.sort.BucketedSort;
 import org.elasticsearch.search.sort.SortOrder;
 
@@ -30,20 +30,20 @@ public abstract class SourceValueFetcherIndexFieldData<T>
         protected final String fieldName;
         protected final ValuesSourceType valuesSourceType;
         protected final ValueFetcher valueFetcher;
-        protected final SourceLookup sourceLookup;
+        protected final SourceProvider sourceProvider;
         protected final ToScriptFieldFactory<T> toScriptFieldFactory;
 
         public Builder(
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<T> toScriptFieldFactory
         ) {
             this.fieldName = fieldName;
             this.valuesSourceType = valuesSourceType;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
             this.toScriptFieldFactory = toScriptFieldFactory;
         }
     }
@@ -51,20 +51,20 @@ public abstract class SourceValueFetcherIndexFieldData<T>
     protected final String fieldName;
     protected final ValuesSourceType valuesSourceType;
     protected final ValueFetcher valueFetcher;
-    protected final SourceLookup sourceLookup;
+    protected final SourceProvider sourceProvider;
     protected final ToScriptFieldFactory<T> toScriptFieldFactory;
 
     protected SourceValueFetcherIndexFieldData(
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<T> toScriptFieldFactory
     ) {
         this.fieldName = fieldName;
         this.valuesSourceType = valuesSourceType;
         this.valueFetcher = valueFetcher;
-        this.sourceLookup = sourceLookup;
+        this.sourceProvider = sourceProvider;
         this.toScriptFieldFactory = toScriptFieldFactory;
     }
 
@@ -112,18 +112,18 @@ public abstract class SourceValueFetcherIndexFieldData<T>
         protected final LeafReaderContext leafReaderContext;
 
         protected final ValueFetcher valueFetcher;
-        protected final SourceLookup sourceLookup;
+        protected final SourceProvider sourceProvider;
 
         public SourceValueFetcherLeafFieldData(
             ToScriptFieldFactory<T> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
             this.toScriptFieldFactory = toScriptFieldFactory;
             this.leafReaderContext = leafReaderContext;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
         }
 
         @Override

server/src/main/java/org/elasticsearch/index/fielddata/SourceValueFetcherMultiGeoPointIndexFieldData.java

@@ -15,7 +15,8 @@ import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -30,10 +31,10 @@ public class SourceValueFetcherMultiGeoPointIndexFieldData extends SourceValueFe
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<MultiGeoPointValues> toScriptFieldFactory
         ) {
-            super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+            super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
         }
 
         @Override
@@ -42,7 +43,7 @@ public class SourceValueFetcherMultiGeoPointIndexFieldData extends SourceValueFe
                 fieldName,
                 valuesSourceType,
                 valueFetcher,
-                sourceLookup,
+                sourceProvider,
                 toScriptFieldFactory
             );
         }
@@ -52,15 +53,15 @@ public class SourceValueFetcherMultiGeoPointIndexFieldData extends SourceValueFe
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<MultiGeoPointValues> toScriptFieldFactory
     ) {
-        super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+        super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
     }
 
     @Override
     public SourceValueFetcherMultiGeoPointLeafFieldData loadDirect(LeafReaderContext context) throws Exception {
-        return new SourceValueFetcherMultiGeoPointLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceLookup);
+        return new SourceValueFetcherMultiGeoPointLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceProvider);
     }
 
     public static class SourceValueFetcherMultiGeoPointLeafFieldData extends
@@ -70,15 +71,15 @@ public class SourceValueFetcherMultiGeoPointIndexFieldData extends SourceValueFe
             ToScriptFieldFactory<MultiGeoPointValues> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceLookup);
+            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         public DocValuesScriptFieldFactory getScriptFieldFactory(String name) {
             return toScriptFieldFactory.getScriptFieldFactory(
-                new MultiGeoPointValues(new SourceValueFetcherMultiGeoPointDocValues(leafReaderContext, valueFetcher, sourceLookup)),
+                new MultiGeoPointValues(new SourceValueFetcherMultiGeoPointDocValues(leafReaderContext, valueFetcher, sourceProvider)),
                 name
             );
         }
@@ -90,18 +91,17 @@ public class SourceValueFetcherMultiGeoPointIndexFieldData extends SourceValueFe
         public SourceValueFetcherMultiGeoPointDocValues(
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(leafReaderContext, valueFetcher, sourceLookup);
+            super(leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public boolean advanceExact(int doc) throws IOException {
-            sourceLookup.setSegmentAndDocument(leafReaderContext, doc);
             values.clear();
-
-            for (Object value : valueFetcher.fetchValues(sourceLookup, doc, Collections.emptyList())) {
+            Source source = sourceProvider.getSource(leafReaderContext, doc);
+            for (Object value : valueFetcher.fetchValues(source, doc, Collections.emptyList())) {
                 assert value instanceof Map && ((Map<Object, Object>) value).get("coordinates") instanceof List;
                 List<Object> coordinates = ((Map<String, List<Object>>) value).get("coordinates");
                 assert coordinates.size() == 2 && coordinates.get(1) instanceof Number && coordinates.get(0) instanceof Number;

server/src/main/java/org/elasticsearch/index/fielddata/SourceValueFetcherSortedBinaryIndexFieldData.java

@@ -15,7 +15,8 @@ import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -31,10 +32,10 @@ public class SourceValueFetcherSortedBinaryIndexFieldData extends SourceValueFet
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<SortedBinaryDocValues> toScriptFieldFactory
         ) {
-            super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+            super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
         }
 
         @Override
@@ -43,7 +44,7 @@ public class SourceValueFetcherSortedBinaryIndexFieldData extends SourceValueFet
                 fieldName,
                 valuesSourceType,
                 valueFetcher,
-                sourceLookup,
+                sourceProvider,
                 toScriptFieldFactory
             );
         }
@@ -53,15 +54,15 @@ public class SourceValueFetcherSortedBinaryIndexFieldData extends SourceValueFet
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<SortedBinaryDocValues> toScriptFieldFactory
     ) {
-        super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+        super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
     }
 
     @Override
     public SourceValueFetcherSortedBinaryLeafFieldData loadDirect(LeafReaderContext context) throws Exception {
-        return new SourceValueFetcherSortedBinaryLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceLookup);
+        return new SourceValueFetcherSortedBinaryLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceProvider);
     }
 
     public static class SourceValueFetcherSortedBinaryLeafFieldData extends SourceValueFetcherLeafFieldData<SortedBinaryDocValues> {
@@ -70,15 +71,15 @@ public class SourceValueFetcherSortedBinaryIndexFieldData extends SourceValueFet
             ToScriptFieldFactory<SortedBinaryDocValues> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceLookup);
+            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         public DocValuesScriptFieldFactory getScriptFieldFactory(String name) {
             return toScriptFieldFactory.getScriptFieldFactory(
-                new SourceValueFetcherSortedBinaryDocValues(leafReaderContext, valueFetcher, sourceLookup),
+                new SourceValueFetcherSortedBinaryDocValues(leafReaderContext, valueFetcher, sourceProvider),
                 name
             );
         }
@@ -89,7 +90,7 @@ public class SourceValueFetcherSortedBinaryIndexFieldData extends SourceValueFet
         private final LeafReaderContext leafReaderContext;
 
         private final ValueFetcher valueFetcher;
-        private final SourceLookup sourceLookup;
+        private final SourceProvider sourceProvider;
 
         private final SortedSet<BytesRef> values;
         private Iterator<BytesRef> iterator;
@@ -97,21 +98,20 @@ public class SourceValueFetcherSortedBinaryIndexFieldData extends SourceValueFet
         public SourceValueFetcherSortedBinaryDocValues(
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
             this.leafReaderContext = leafReaderContext;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
 
             values = new TreeSet<>();
         }
 
         @Override
         public boolean advanceExact(int doc) throws IOException {
-            sourceLookup.setSegmentAndDocument(leafReaderContext, doc);
             values.clear();
-
-            for (Object object : valueFetcher.fetchValues(sourceLookup, doc, Collections.emptyList())) {
+            Source source = sourceProvider.getSource(leafReaderContext, doc);
+            for (Object object : valueFetcher.fetchValues(source, doc, Collections.emptyList())) {
                 values.add(new BytesRef(object.toString()));
             }
 

server/src/main/java/org/elasticsearch/index/fielddata/SourceValueFetcherSortedBooleanIndexFieldData.java

@@ -15,7 +15,8 @@ import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -28,10 +29,10 @@ public class SourceValueFetcherSortedBooleanIndexFieldData extends SourceValueFe
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory
         ) {
-            super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+            super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
         }
 
         @Override
@@ -40,7 +41,7 @@ public class SourceValueFetcherSortedBooleanIndexFieldData extends SourceValueFe
                 fieldName,
                 valuesSourceType,
                 valueFetcher,
-                sourceLookup,
+                sourceProvider,
                 toScriptFieldFactory
             );
         }
@@ -50,15 +51,15 @@ public class SourceValueFetcherSortedBooleanIndexFieldData extends SourceValueFe
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory
     ) {
-        super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+        super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
     }
 
     @Override
     public SourceValueFetcherLeafFieldData<SortedNumericDocValues> loadDirect(LeafReaderContext context) throws Exception {
-        return new SourceValueFetcherSortedBooleanLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceLookup);
+        return new SourceValueFetcherSortedBooleanLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceProvider);
     }
 
     private static class SourceValueFetcherSortedBooleanLeafFieldData extends SourceValueFetcherLeafFieldData<SortedNumericDocValues> {
@@ -67,15 +68,15 @@ public class SourceValueFetcherSortedBooleanIndexFieldData extends SourceValueFe
             ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceLookup);
+            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         public DocValuesScriptFieldFactory getScriptFieldFactory(String name) {
             return toScriptFieldFactory.getScriptFieldFactory(
-                new SourceValueFetcherSortedBooleanDocValues(leafReaderContext, valueFetcher, sourceLookup),
+                new SourceValueFetcherSortedBooleanDocValues(leafReaderContext, valueFetcher, sourceProvider),
                 name
             );
         }
@@ -86,7 +87,7 @@ public class SourceValueFetcherSortedBooleanIndexFieldData extends SourceValueFe
         private final LeafReaderContext leafReaderContext;
 
         private final ValueFetcher valueFetcher;
-        private final SourceLookup sourceLookup;
+        private final SourceProvider sourceProvider;
 
         private int trueCount;
         private int falseCount;
@@ -95,21 +96,19 @@ public class SourceValueFetcherSortedBooleanIndexFieldData extends SourceValueFe
         SourceValueFetcherSortedBooleanDocValues(
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
             this.leafReaderContext = leafReaderContext;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
         }
 
         @Override
         public boolean advanceExact(int doc) throws IOException {
-            sourceLookup.setSegmentAndDocument(leafReaderContext, doc);
-
             trueCount = 0;
             falseCount = 0;
-
-            for (Object value : valueFetcher.fetchValues(sourceLookup, doc, Collections.emptyList())) {
+            Source source = sourceProvider.getSource(leafReaderContext, doc);
+            for (Object value : valueFetcher.fetchValues(source, doc, Collections.emptyList())) {
                 assert value instanceof Boolean;
                 if ((Boolean) value) {
                     ++trueCount;

server/src/main/java/org/elasticsearch/index/fielddata/SourceValueFetcherSortedDoubleIndexFieldData.java

@@ -14,7 +14,8 @@ import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -30,10 +31,10 @@ public class SourceValueFetcherSortedDoubleIndexFieldData extends SourceValueFet
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<SortedNumericDoubleValues> toScriptFieldFactory
         ) {
-            super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+            super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
         }
 
         @Override
@@ -42,7 +43,7 @@ public class SourceValueFetcherSortedDoubleIndexFieldData extends SourceValueFet
                 fieldName,
                 valuesSourceType,
                 valueFetcher,
-                sourceLookup,
+                sourceProvider,
                 toScriptFieldFactory
             );
         }
@@ -52,15 +53,15 @@ public class SourceValueFetcherSortedDoubleIndexFieldData extends SourceValueFet
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<SortedNumericDoubleValues> toScriptFieldFactory
     ) {
-        super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+        super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
     }
 
     @Override
     public SourceValueFetcherLeafFieldData<SortedNumericDoubleValues> loadDirect(LeafReaderContext context) throws Exception {
-        return new SourceValueFetcherSortedDoubleLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceLookup);
+        return new SourceValueFetcherSortedDoubleLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceProvider);
     }
 
     private static class SourceValueFetcherSortedDoubleLeafFieldData extends SourceValueFetcherLeafFieldData<SortedNumericDoubleValues> {
@@ -69,15 +70,15 @@ public class SourceValueFetcherSortedDoubleIndexFieldData extends SourceValueFet
             ToScriptFieldFactory<SortedNumericDoubleValues> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceLookup);
+            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         public DocValuesScriptFieldFactory getScriptFieldFactory(String name) {
             return toScriptFieldFactory.getScriptFieldFactory(
-                new SourceValueFetcherSortedNumericDoubleValues(leafReaderContext, valueFetcher, sourceLookup),
+                new SourceValueFetcherSortedNumericDoubleValues(leafReaderContext, valueFetcher, sourceProvider),
                 name
             );
         }
@@ -88,7 +89,7 @@ public class SourceValueFetcherSortedDoubleIndexFieldData extends SourceValueFet
         private final LeafReaderContext leafReaderContext;
 
         private final ValueFetcher valueFetcher;
-        private final SourceLookup sourceLookup;
+        private final SourceProvider sourceProvider;
 
         private final List<Double> values;
         private Iterator<Double> iterator;
@@ -96,21 +97,20 @@ public class SourceValueFetcherSortedDoubleIndexFieldData extends SourceValueFet
         private SourceValueFetcherSortedNumericDoubleValues(
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
             this.leafReaderContext = leafReaderContext;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
 
             values = new ArrayList<>();
         }
 
         @Override
         public boolean advanceExact(int doc) throws IOException {
-            sourceLookup.setSegmentAndDocument(leafReaderContext, doc);
             values.clear();
-
-            for (Object value : valueFetcher.fetchValues(sourceLookup, doc, Collections.emptyList())) {
+            Source source = sourceProvider.getSource(leafReaderContext, doc);
+            for (Object value : valueFetcher.fetchValues(source, doc, Collections.emptyList())) {
                 assert value instanceof Number;
                 values.add(((Number) value).doubleValue());
             }

server/src/main/java/org/elasticsearch/index/fielddata/SourceValueFetcherSortedNumericIndexFieldData.java

@@ -15,7 +15,8 @@ import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -31,10 +32,10 @@ public class SourceValueFetcherSortedNumericIndexFieldData extends SourceValueFe
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory
         ) {
-            super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+            super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
         }
 
         @Override
@@ -43,7 +44,7 @@ public class SourceValueFetcherSortedNumericIndexFieldData extends SourceValueFe
                 fieldName,
                 valuesSourceType,
                 valueFetcher,
-                sourceLookup,
+                sourceProvider,
                 toScriptFieldFactory
             );
         }
@@ -53,15 +54,15 @@ public class SourceValueFetcherSortedNumericIndexFieldData extends SourceValueFe
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory
     ) {
-        super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+        super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
     }
 
     @Override
     public SourceValueFetcherSortedNumericLeafFieldData loadDirect(LeafReaderContext context) throws Exception {
-        return new SourceValueFetcherSortedNumericLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceLookup);
+        return new SourceValueFetcherSortedNumericLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceProvider);
     }
 
     public static class SourceValueFetcherSortedNumericLeafFieldData extends SourceValueFetcherLeafFieldData<SortedNumericDocValues> {
@@ -70,15 +71,15 @@ public class SourceValueFetcherSortedNumericIndexFieldData extends SourceValueFe
             ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceLookup);
+            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         public DocValuesScriptFieldFactory getScriptFieldFactory(String name) {
             return toScriptFieldFactory.getScriptFieldFactory(
-                new SourceValueFetcherSortedNumericDocValues(leafReaderContext, valueFetcher, sourceLookup),
+                new SourceValueFetcherSortedNumericDocValues(leafReaderContext, valueFetcher, sourceProvider),
                 name
             );
         }
@@ -89,7 +90,7 @@ public class SourceValueFetcherSortedNumericIndexFieldData extends SourceValueFe
         protected final LeafReaderContext leafReaderContext;
 
         protected final ValueFetcher valueFetcher;
-        protected final SourceLookup sourceLookup;
+        protected final SourceProvider sourceProvider;
 
         protected final List<Long> values;
         protected Iterator<Long> iterator;
@@ -97,21 +98,20 @@ public class SourceValueFetcherSortedNumericIndexFieldData extends SourceValueFe
         public SourceValueFetcherSortedNumericDocValues(
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
             this.leafReaderContext = leafReaderContext;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
 
             values = new ArrayList<>();
         }
 
         @Override
         public boolean advanceExact(int doc) throws IOException {
-            sourceLookup.setSegmentAndDocument(leafReaderContext, doc);
             values.clear();
-
-            for (Object value : valueFetcher.fetchValues(sourceLookup, doc, Collections.emptyList())) {
+            Source source = sourceProvider.getSource(leafReaderContext, doc);
+            for (Object value : valueFetcher.fetchValues(source, doc, Collections.emptyList())) {
                 assert value instanceof Number;
                 values.add(((Number) value).longValue());
             }

server/src/main/java/org/elasticsearch/index/fieldvisitor/StoredFieldLoader.java

@@ -60,6 +60,23 @@ public abstract class StoredFieldLoader {
         };
     }
 
+    /**
+     * Creates a StoredFieldLoader tuned for sequential reads of _source
+     */
+    public static StoredFieldLoader sequentialSource() {
+        return new StoredFieldLoader() {
+            @Override
+            public LeafStoredFieldLoader getLoader(LeafReaderContext ctx, int[] docs) {
+                return new ReaderStoredFieldLoader(sequentialReader(ctx), true, Set.of());
+            }
+
+            @Override
+            public List<String> fieldsToLoad() {
+                return List.of();
+            }
+        };
+    }
+
     /**
      * Creates a no-op StoredFieldLoader that will not load any fields from disk
      */
@@ -82,7 +99,15 @@ public abstract class StoredFieldLoader {
         if (docs == null) {
             return leafReader::document;
         }
-        if (leafReader instanceof SequentialStoredFieldsLeafReader lf && docs.length > 10 && hasSequentialDocs(docs)) {
+        if (docs.length > 10 && hasSequentialDocs(docs)) {
+            return sequentialReader(ctx);
+        }
+        return leafReader::document;
+    }
+
+    private static CheckedBiConsumer<Integer, FieldsVisitor, IOException> sequentialReader(LeafReaderContext ctx) {
+        LeafReader leafReader = ctx.reader();
+        if (leafReader instanceof SequentialStoredFieldsLeafReader lf) {
             return lf.getSequentialStoredFieldsReader()::visitDocument;
         }
         return leafReader::document;

server/src/main/java/org/elasticsearch/index/get/GetResult.java

@@ -24,7 +24,7 @@ import org.elasticsearch.index.mapper.IgnoredFieldMapper;
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.mapper.SourceFieldMapper;
 import org.elasticsearch.rest.action.document.RestMultiGetAction;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.xcontent.ToXContentObject;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentParser;
@@ -225,7 +225,7 @@ public class GetResult implements Writeable, Iterable<DocumentField>, ToXContent
             return sourceAsMap;
         }
 
-        sourceAsMap = SourceLookup.sourceAsMap(source);
+        sourceAsMap = Source.fromBytes(source).source();
         return sourceAsMap;
     }
 

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

@@ -280,7 +280,7 @@ public class BooleanFieldMapper extends FieldMapper {
                     name(),
                     CoreValuesSourceType.BOOLEAN,
                     sourceValueFetcher(sourcePaths),
-                    searchLookup.source(),
+                    searchLookup,
                     BooleanDocValuesField::new
                 );
             }

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

@@ -789,7 +789,7 @@ public final class DateFieldMapper extends FieldMapper {
                     name(),
                     resolution.numericType().getValuesSourceType(),
                     sourceValueFetcher(sourcePaths),
-                    searchLookup.source(),
+                    searchLookup,
                     resolution.getDefaultToScriptFieldFactory()
                 );
             }

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

@@ -21,7 +21,7 @@ import org.elasticsearch.index.fielddata.IndexFieldDataCache;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentParser;
 import org.elasticsearch.xcontent.XContentParserConfiguration;
@@ -133,7 +133,7 @@ public final class DocumentParser {
             (ft, lookup, fto) -> ft.fielddataBuilder(
                 new FieldDataContext(context.indexSettings().getIndex().getName(), lookup, context.mappingLookup()::sourcePaths, fto)
             ).build(new IndexFieldDataCache.None(), new NoneCircuitBreakerService()),
-            new SourceLookup.ReaderSourceProvider()
+            (ctx, doc) -> Source.fromBytes(context.sourceToParse().source())
         );
         // field scripts can be called both by the loop at the end of this method and via
         // the document reader, so to ensure that we don't run them multiple times we

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

@@ -389,7 +389,7 @@ public class GeoPointFieldMapper extends AbstractPointGeometryFieldMapper<GeoPoi
                     name(),
                     CoreValuesSourceType.GEOPOINT,
                     valueFetcher(sourcePaths, null, null),
-                    searchLookup.source(),
+                    searchLookup,
                     GeoPointDocValuesField::new
                 );
             }

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

@@ -735,7 +735,7 @@ public final class KeywordFieldMapper extends FieldMapper {
                 name(),
                 CoreValuesSourceType.KEYWORD,
                 sourceValueFetcher(sourcePaths),
-                fieldDataContext.lookupSupplier().get().source(),
+                fieldDataContext.lookupSupplier().get(),
                 KeywordDocValuesField::new
             );
         }

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

@@ -13,7 +13,6 @@ import org.elasticsearch.cluster.metadata.DataStream;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.analysis.IndexAnalyzers;
 import org.elasticsearch.index.analysis.NamedAnalyzer;
-import org.elasticsearch.search.lookup.SourceLookup;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -492,18 +491,4 @@ public final class MappingLookup {
             throw new MapperParsingException("Field [" + name + "] attempted to shadow a time_series_metric");
         }
     }
-
-    /**
-     * Returns a SourceProvider describing how to read the source. If using synthetic source, returns the null source provider
-     * expecting the source to either be provided later by a fetch phase or not be accessed at all (as in scripts).
-     * @return
-     */
-    public SourceLookup.SourceProvider getSourceProvider() {
-        SourceFieldMapper sourceMapper = (SourceFieldMapper) getMapper("_source");
-        if (sourceMapper == null || sourceMapper.isSynthetic() == false) {
-            return new SourceLookup.ReaderSourceProvider();
-        } else {
-            return new SourceLookup.NullSourceProvider();
-        }
-    }
 }

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

@@ -56,7 +56,7 @@ import org.elasticsearch.search.aggregations.support.TimeSeriesValuesSourceType;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 import org.elasticsearch.search.lookup.FieldValues;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentParser;
 import org.elasticsearch.xcontent.XContentParser.Token;
@@ -413,14 +413,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedDoubleIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     HalfFloatDocValuesField::new
                 );
             }
@@ -564,14 +564,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedDoubleIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     FloatDocValuesField::new
                 );
             }
@@ -693,14 +693,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedDoubleIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     DoubleDocValuesField::new
                 );
             }
@@ -797,14 +797,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedNumericIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     ByteDocValuesField::new
                 );
             }
@@ -886,14 +886,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedNumericIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     ShortDocValuesField::new
                 );
             }
@@ -1042,14 +1042,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedNumericIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     IntegerDocValuesField::new
                 );
             }
@@ -1168,14 +1168,14 @@ public class NumberFieldMapper extends FieldMapper {
             public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
                 String name,
                 ValuesSourceType valuesSourceType,
-                SourceLookup sourceLookup,
+                SourceProvider sourceProvider,
                 ValueFetcher valueFetcher
             ) {
                 return new SourceValueFetcherSortedNumericIndexFieldData.Builder(
                     name,
                     valuesSourceType,
                     valueFetcher,
-                    sourceLookup,
+                    sourceProvider,
                     LongDocValuesField::new
                 );
             }
@@ -1415,7 +1415,7 @@ public class NumberFieldMapper extends FieldMapper {
         public IndexFieldData.Builder getValueFetcherFieldDataBuilder(
             String name,
             ValuesSourceType valuesSourceType,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ValueFetcher valueFetcher
         ) {
             throw new UnsupportedOperationException("not supported for source fallback");
@@ -1592,12 +1592,7 @@ public class NumberFieldMapper extends FieldMapper {
             if (operation == FielddataOperation.SCRIPT) {
                 SearchLookup searchLookup = fieldDataContext.lookupSupplier().get();
                 Set<String> sourcePaths = fieldDataContext.sourcePathsLookup().apply(name());
-                return type.getValueFetcherFieldDataBuilder(
-                    name(),
-                    valuesSourceType,
-                    searchLookup.source(),
-                    sourceValueFetcher(sourcePaths)
-                );
+                return type.getValueFetcherFieldDataBuilder(name(), valuesSourceType, searchLookup, sourceValueFetcher(sourcePaths));
             }
 
             throw new IllegalStateException("unknown field data type [" + operation.name() + "]");

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

@@ -101,6 +101,11 @@ public class SourceFieldMapper extends MetadataFieldMapper {
             super(Defaults.NAME);
         }
 
+        public Builder setSynthetic() {
+            this.mode.setValue(Mode.SYNTHETIC);
+            return this;
+        }
+
         @Override
         protected Parameter<?>[] getParameters() {
             return new Parameter<?>[] { enabled, mode, includes, excludes };

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

@@ -1015,7 +1015,7 @@ public class TextFieldMapper extends FieldMapper {
                 name(),
                 CoreValuesSourceType.KEYWORD,
                 SourceValueFetcher.toString(fieldDataContext.sourcePathsLookup().apply(name())),
-                fieldDataContext.lookupSupplier().get().source(),
+                fieldDataContext.lookupSupplier().get(),
                 TextDocValuesField::new
             );
         }

server/src/main/java/org/elasticsearch/index/query/SearchExecutionContext.java

@@ -59,7 +59,7 @@ import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.search.NestedDocuments;
 import org.elasticsearch.search.aggregations.support.ValuesSourceRegistry;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.transport.RemoteClusterAware;
 import org.elasticsearch.xcontent.XContentParserConfiguration;
 
@@ -491,21 +491,33 @@ public class SearchExecutionContext extends QueryRewriteContext {
      */
     public SearchLookup lookup() {
         if (this.lookup == null) {
-            SourceLookup.SourceProvider sourceProvider = mappingLookup == null
-                ? new SourceLookup.ReaderSourceProvider()
-                : mappingLookup.getSourceProvider();
-            this.lookup = new SearchLookup(
-                this::getFieldType,
-                (fieldType, searchLookup, fielddataOperation) -> indexFieldDataLookup.apply(
-                    fieldType,
-                    new FieldDataContext(fullyQualifiedIndex.getName(), searchLookup, this::sourcePath, fielddataOperation)
-                ),
-                sourceProvider
-            );
+            SourceProvider sourceProvider = isSourceSynthetic()
+                ? (ctx, doc) -> { throw new IllegalArgumentException("Cannot access source from scripts in synthetic mode"); }
+                : SourceProvider.fromStoredFields();
+            setSourceProvider(sourceProvider);
         }
         return this.lookup;
     }
 
+    /**
+     * Replace the standard source provider on the SearchLookup
+     *
+     * Note that this will replace the current SearchLookup with a new one, but will not update
+     * the source provider on previously build lookups. This method should only be called before
+     * IndexReader access by the current context
+     */
+    public void setSourceProvider(SourceProvider sourceProvider) {
+        // TODO can we assert that this is only called during FetchPhase?
+        this.lookup = new SearchLookup(
+            this::getFieldType,
+            (fieldType, searchLookup, fielddataOperation) -> indexFieldDataLookup.apply(
+                fieldType,
+                new FieldDataContext(fullyQualifiedIndex.getName(), searchLookup, this::sourcePath, fielddataOperation)
+            ),
+            sourceProvider
+        );
+    }
+
     public NestedScope nestedScope() {
         return nestedScope;
     }

server/src/main/java/org/elasticsearch/script/AbstractFieldScript.java

@@ -12,13 +12,14 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.elasticsearch.common.xcontent.support.XContentMapValues;
 import org.elasticsearch.index.mapper.OnScriptError;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 import static org.elasticsearch.core.TimeValue.timeValueMillis;
 
@@ -62,13 +63,14 @@ public abstract class AbstractFieldScript extends DocBasedScript {
         );
     }
 
+    @SuppressWarnings("unchecked")
     private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of(
         "_source",
-        value -> ((SourceLookup) value).source()
+        value -> ((Supplier<Source>) value).get().source()
     );
 
     protected final String fieldName;
-    protected final SourceLookup sourceLookup;
+    protected final Supplier<Source> source;
     private final Map<String, Object> params;
     private final OnScriptError onScriptError;
 
@@ -79,13 +81,16 @@ public abstract class AbstractFieldScript extends DocBasedScript {
         LeafReaderContext ctx,
         OnScriptError onScriptError
     ) {
-        super(new DocValuesDocReader(searchLookup, ctx));
+        this(fieldName, params, new DocValuesDocReader(searchLookup, ctx), onScriptError);
+    }
+
+    private AbstractFieldScript(String fieldName, Map<String, Object> params, DocReader docReader, OnScriptError onScriptError) {
+        super(docReader);
         this.fieldName = fieldName;
-        Map<String, Object> docAsMap = docAsMap();
-        this.sourceLookup = (SourceLookup) docAsMap.get("_source");
+        this.source = docReader.source();
         params = new HashMap<>(params);
-        params.put("_source", sourceLookup);
-        params.put("_fields", docAsMap.get("_fields"));
+        params.put("_source", this.source);
+        params.put("_fields", docReader.docAsMap().get("_fields"));
         this.params = new DynamicMap(params, PARAMS_FUNCTIONS);
         this.onScriptError = onScriptError;
     }
@@ -98,7 +103,7 @@ public abstract class AbstractFieldScript extends DocBasedScript {
     }
 
     protected List<Object> extractFromSource(String path) {
-        return XContentMapValues.extractRawValues(path, sourceLookup.source());
+        return XContentMapValues.extractRawValues(path, source.get().source());
     }
 
     protected final void emitFromCompositeScript(CompositeFieldScript compositeFieldScript) {

server/src/main/java/org/elasticsearch/script/AbstractSortScript.java

@@ -12,16 +12,18 @@ import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.lucene.ScorerAware;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 abstract class AbstractSortScript extends DocBasedScript implements ScorerAware {
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DynamicMap.class);
+    @SuppressWarnings("unchecked")
     private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of("doc", value -> {
         deprecationLogger.warn(
             DeprecationCategory.SCRIPTING,
@@ -36,7 +38,7 @@ abstract class AbstractSortScript extends DocBasedScript implements ScorerAware
             "Accessing variable [doc] via [params._doc] from within an sort-script " + "is deprecated in favor of directly accessing [doc]."
         );
         return value;
-    }, "_source", value -> ((SourceLookup) value).source());
+    }, "_source", value -> ((Supplier<Source>) value).get().source());
 
     /**
      * The generic runtime parameters for the script.

server/src/main/java/org/elasticsearch/script/AggregationScript.java

@@ -14,12 +14,13 @@ import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.lucene.ScorerAware;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 public abstract class AggregationScript extends DocBasedScript implements ScorerAware {
 
@@ -28,6 +29,8 @@ public abstract class AggregationScript extends DocBasedScript implements Scorer
     public static final ScriptContext<Factory> CONTEXT = new ScriptContext<>("aggs", Factory.class);
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DynamicMap.class);
+
+    @SuppressWarnings("unchecked")
     private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of("doc", value -> {
         deprecationLogger.warn(
             DeprecationCategory.SCRIPTING,
@@ -44,7 +47,7 @@ public abstract class AggregationScript extends DocBasedScript implements Scorer
                 + "is deprecated in favor of directly accessing [doc]."
         );
         return value;
-    }, "_source", value -> ((SourceLookup) value).source());
+    }, "_source", value -> ((Supplier<Source>) value).get().source());
 
     /**
      * The generic runtime parameters for the script.
@@ -59,9 +62,13 @@ public abstract class AggregationScript extends DocBasedScript implements Scorer
     private Object value;
 
     public AggregationScript(Map<String, Object> params, SearchLookup lookup, LeafReaderContext leafContext) {
-        super(new DocValuesDocReader(lookup, leafContext));
+        this(params, new DocValuesDocReader(lookup, leafContext));
+    }
+
+    private AggregationScript(Map<String, Object> params, DocReader docReader) {
+        super(docReader);
         this.params = new DynamicMap(new HashMap<>(params), PARAMS_FUNCTIONS);
-        this.params.putAll(docAsMap());
+        this.params.putAll(docReader.docAsMap());
     }
 
     protected AggregationScript() {

server/src/main/java/org/elasticsearch/script/DocBasedScript.java

@@ -11,9 +11,12 @@ package org.elasticsearch.script;
 import org.elasticsearch.index.fielddata.ScriptDocValues;
 import org.elasticsearch.script.field.EmptyField;
 import org.elasticsearch.script.field.Field;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.util.Collections;
 import java.util.Map;
+import java.util.function.Supplier;
 import java.util.stream.Stream;
 
 public abstract class DocBasedScript {
@@ -53,6 +56,13 @@ public abstract class DocBasedScript {
         return docReader.docAsMap();
     }
 
+    public Supplier<Source> source() {
+        if (docReader == null) {
+            return () -> Source.empty(XContentType.JSON);
+        }
+        return docReader.source();
+    }
+
     /**
      * The doc lookup for the Lucene segment this script was created for.
      */

server/src/main/java/org/elasticsearch/script/DocReader.java

@@ -10,8 +10,10 @@ package org.elasticsearch.script;
 
 import org.elasticsearch.index.fielddata.ScriptDocValues;
 import org.elasticsearch.script.field.Field;
+import org.elasticsearch.search.lookup.Source;
 
 import java.util.Map;
+import java.util.function.Supplier;
 import java.util.stream.Stream;
 
 /**
@@ -36,4 +38,7 @@ public interface DocReader {
 
     /** Old-style doc['field'] access */
     Map<String, ScriptDocValues<?>> doc();
+
+    /** Helper for source access */
+    Supplier<Source> source();
 }

server/src/main/java/org/elasticsearch/script/DocValuesDocReader.java

@@ -15,8 +15,10 @@ import org.elasticsearch.script.field.Field;
 import org.elasticsearch.search.lookup.LeafDocLookup;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.util.Map;
+import java.util.function.Supplier;
 import java.util.stream.Stream;
 
 /**
@@ -73,4 +75,9 @@ public class DocValuesDocReader implements DocReader, LeafReaderContextSupplier
     public LeafReaderContext getLeafReaderContext() {
         return leafReaderContext;
     }
+
+    @Override
+    public Supplier<Source> source() {
+        return leafSearchLookup.source();
+    }
 }

server/src/main/java/org/elasticsearch/script/FieldScript.java

@@ -12,12 +12,13 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 /**
  * A script to produce dynamic values for return fields.
@@ -27,6 +28,8 @@ public abstract class FieldScript extends DocBasedScript {
     public static final String[] PARAMETERS = {};
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DynamicMap.class);
+
+    @SuppressWarnings("unchecked")
     private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of("doc", value -> {
         deprecationLogger.warn(
             DeprecationCategory.SCRIPTING,
@@ -42,15 +45,19 @@ public abstract class FieldScript extends DocBasedScript {
                 + "is deprecated in favor of directly accessing [doc]."
         );
         return value;
-    }, "_source", value -> ((SourceLookup) value).source());
+    }, "_source", value -> ((Supplier<Source>) value).get().source());
 
     /** The generic runtime parameters for the script. */
     private final Map<String, Object> params;
 
     public FieldScript(Map<String, Object> params, SearchLookup lookup, LeafReaderContext leafContext) {
-        super(new DocValuesDocReader(lookup, leafContext));
+        this(params, new DocValuesDocReader(lookup, leafContext));
+    }
+
+    private FieldScript(Map<String, Object> params, DocReader docReader) {
+        super(docReader);
         params = new HashMap<>(params);
-        params.putAll(docAsMap());
+        params.putAll(docReader.docAsMap());
         this.params = new DynamicMap(params, PARAMS_FUNCTIONS);
     }
 

server/src/main/java/org/elasticsearch/script/GeoPointFieldScript.java

@@ -138,7 +138,7 @@ public abstract class GeoPointFieldScript extends AbstractFieldScript {
 
     @Override
     protected List<Object> extractFromSource(String path) {
-        Object value = XContentMapValues.extractValue(path, sourceLookup.source());
+        Object value = XContentMapValues.extractValue(path, source.get().source());
         if (value instanceof List<?>) {
             @SuppressWarnings("unchecked")
             List<Object> list = (List<Object>) value;

server/src/main/java/org/elasticsearch/script/ScoreScript.java

@@ -12,7 +12,7 @@ import org.apache.lucene.search.Scorable;
 import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
@@ -20,6 +20,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.function.DoubleSupplier;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 /**
  * A script used for adjusting the score on a per document basis.
@@ -51,6 +52,7 @@ public abstract class ScoreScript extends DocBasedScript {
     }
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DynamicMap.class);
+    @SuppressWarnings("unchecked")
     private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of("doc", value -> {
         deprecationLogger.warn(
             DeprecationCategory.SCRIPTING,
@@ -66,7 +68,7 @@ public abstract class ScoreScript extends DocBasedScript {
                 + "is deprecated in favor of directly accessing [doc]."
         );
         return value;
-    }, "_source", value -> ((SourceLookup) value).source());
+    }, "_source", value -> ((Supplier<Source>) value).get().source());
 
     public static final String[] PARAMETERS = new String[] { "explanation" };
 

server/src/main/java/org/elasticsearch/script/ScriptedMetricAggContexts.java

@@ -15,13 +15,14 @@ import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.index.fielddata.ScriptDocValues;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 public class ScriptedMetricAggContexts {
 
@@ -55,6 +56,8 @@ public class ScriptedMetricAggContexts {
     public abstract static class MapScript extends DocBasedScript {
 
         private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DynamicMap.class);
+
+        @SuppressWarnings("unchecked")
         private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of("doc", value -> {
             deprecationLogger.warn(
                 DeprecationCategory.SCRIPTING,
@@ -79,17 +82,23 @@ public class ScriptedMetricAggContexts {
                     + "is deprecated in favor of using [state]."
             );
             return value;
-        }, "_source", value -> ((SourceLookup) value).source());
+        }, "_source", value -> ((Supplier<Source>) value).get().source());
 
         private final Map<String, Object> params;
         private final Map<String, Object> state;
         private Scorable scorer;
 
         public MapScript(Map<String, Object> params, Map<String, Object> state, SearchLookup lookup, LeafReaderContext leafContext) {
-            super(leafContext == null ? null : new DocValuesDocReader(lookup, leafContext));
+            this(params, state, leafContext == null ? null : new DocValuesDocReader(lookup, leafContext));
+        }
+
+        private MapScript(Map<String, Object> params, Map<String, Object> state, DocReader docReader) {
+            super(docReader);
             this.state = state;
             params = new HashMap<>(params); // copy params so we aren't modifying input
-            params.putAll(docAsMap()); // add lookup vars
+            if (docReader != null) {
+                params.putAll(docReader.docAsMap()); // add lookup vars
+            }
             this.params = new DynamicMap(params, PARAMS_FUNCTIONS); // wrap with deprecations
         }
 

server/src/main/java/org/elasticsearch/script/TermsSetQueryScript.java

@@ -13,12 +13,13 @@ import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.index.fielddata.ScriptDocValues;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 public abstract class TermsSetQueryScript {
 
@@ -27,6 +28,7 @@ public abstract class TermsSetQueryScript {
     public static final ScriptContext<Factory> CONTEXT = new ScriptContext<>("terms_set", Factory.class);
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DynamicMap.class);
+    @SuppressWarnings("unchecked")
     private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of("doc", value -> {
         deprecationLogger.warn(
             DeprecationCategory.SCRIPTING,
@@ -43,7 +45,7 @@ public abstract class TermsSetQueryScript {
                 + "is deprecated in favor of directly accessing [doc]."
         );
         return value;
-    }, "_source", value -> ((SourceLookup) value).source());
+    }, "_source", value -> ((Supplier<Source>) value).get().source());
 
     /**
      * The generic runtime parameters for the script.

server/src/main/java/org/elasticsearch/search/SearchHit.java

@@ -33,7 +33,6 @@ import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.search.fetch.subphase.LookupField;
 import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;
 import org.elasticsearch.search.lookup.Source;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.transport.RemoteClusterAware;
 import org.elasticsearch.xcontent.ConstructingObjectParser;
 import org.elasticsearch.xcontent.ObjectParser;
@@ -402,7 +401,7 @@ public final class SearchHit implements Writeable, ToXContentObject, Iterable<Do
             return sourceAsMap;
         }
 
-        sourceAsMap = SourceLookup.sourceAsMap(source);
+        sourceAsMap = Source.fromBytes(source).source();
         return sourceAsMap;
     }
 

server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/SignificantTextAggregatorFactory.java

@@ -15,9 +15,11 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.BytesRefBuilder;
 import org.elasticsearch.ElasticsearchStatusException;
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.BytesRefHash;
 import org.elasticsearch.common.util.ObjectArray;
+import org.elasticsearch.common.xcontent.support.XContentMapValues;
 import org.elasticsearch.core.Releasables;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.TextSearchInfo;
@@ -43,7 +45,9 @@ import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregator.Bucket
 import org.elasticsearch.search.aggregations.bucket.terms.heuristic.SignificanceHeuristic;
 import org.elasticsearch.search.aggregations.support.AggregationContext;
 import org.elasticsearch.search.aggregations.support.SamplingContext;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceFilter;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.search.profile.Timer;
 
 import java.io.IOException;
@@ -224,7 +228,7 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
             .toArray(String[]::new);
         if (context.profiling()) {
             return new ProfilingSignificantTextCollectorSource(
-                context.lookup().source(),
+                context.lookup(),
                 context.bigArrays(),
                 fieldType,
                 analyzer,
@@ -233,7 +237,7 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
             );
         }
         return new SignificantTextCollectorSource(
-            context.lookup().source(),
+            context.lookup(),
             context.bigArrays(),
             fieldType,
             analyzer,
@@ -243,7 +247,8 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
     }
 
     private static class SignificantTextCollectorSource implements MapStringTermsAggregator.CollectorSource {
-        private final SourceLookup sourceLookup;
+        private final SourceProvider sourceProvider;
+        private final SourceFilter sourceFilter;
         private final BigArrays bigArrays;
         private final MappedFieldType fieldType;
         private final Analyzer analyzer;
@@ -252,18 +257,19 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
         private ObjectArray<DuplicateByteSequenceSpotter> dupSequenceSpotters;
 
         SignificantTextCollectorSource(
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             BigArrays bigArrays,
             MappedFieldType fieldType,
             Analyzer analyzer,
             String[] sourceFieldNames,
             boolean filterDuplicateText
         ) {
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
             this.bigArrays = bigArrays;
             this.fieldType = fieldType;
             this.analyzer = analyzer;
             this.sourceFieldNames = sourceFieldNames;
+            this.sourceFilter = new SourceFilter(sourceFieldNames, Strings.EMPTY_ARRAY);
             dupSequenceSpotters = filterDuplicateText ? bigArrays.newObjectArray(1) : null;
         }
 
@@ -306,12 +312,11 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
                 }
 
                 private void collectFromSource(int doc, long owningBucketOrd, DuplicateByteSequenceSpotter spotter) throws IOException {
-                    sourceLookup.setSegmentAndDocument(ctx, doc);
                     BytesRefHash inDocTerms = new BytesRefHash(256, bigArrays);
-
+                    Source source = sourceProvider.getSource(ctx, doc).filter(sourceFilter);
                     try {
                         for (String sourceField : sourceFieldNames) {
-                            Iterator<String> itr = extractRawValues(sourceField).stream().map(obj -> {
+                            Iterator<String> itr = extractRawValues(source, sourceField).stream().map(obj -> {
                                 if (obj == null) {
                                     return null;
                                 }
@@ -400,8 +405,8 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
         /**
          * Extract values from {@code _source}.
          */
-        protected List<Object> extractRawValues(String field) {
-            return sourceLookup.extractRawValuesWithoutCaching(field);
+        protected List<Object> extractRawValues(Source source, String field) {
+            return XContentMapValues.extractRawValues(field, source.source());
         }
 
         @Override
@@ -417,14 +422,14 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
         private long charsFetched;
 
         private ProfilingSignificantTextCollectorSource(
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             BigArrays bigArrays,
             MappedFieldType fieldType,
             Analyzer analyzer,
             String[] sourceFieldNames,
             boolean filterDuplicateText
         ) {
-            super(sourceLookup, bigArrays, fieldType, analyzer, sourceFieldNames, filterDuplicateText);
+            super(sourceProvider, bigArrays, fieldType, analyzer, sourceFieldNames, filterDuplicateText);
         }
 
         @Override
@@ -464,10 +469,10 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory {
         }
 
         @Override
-        protected List<Object> extractRawValues(String field) {
+        protected List<Object> extractRawValues(Source source, String field) {
             extract.start();
             try {
-                return super.extractRawValues(field);
+                return super.extractRawValues(source, field);
             } finally {
                 extract.stop();
             }

server/src/main/java/org/elasticsearch/search/fetch/FetchPhase.java

@@ -26,7 +26,7 @@ import org.elasticsearch.search.fetch.subphase.InnerHitsContext;
 import org.elasticsearch.search.fetch.subphase.InnerHitsPhase;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.search.lookup.Source;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.search.profile.ProfileResult;
 import org.elasticsearch.search.profile.Profilers;
 import org.elasticsearch.tasks.TaskCancelledException;
@@ -84,6 +84,16 @@ public class FetchPhase {
         }
     }
 
+    private static class PreloadedSourceProvider implements SourceProvider {
+
+        Source source;
+
+        @Override
+        public Source getSource(LeafReaderContext ctx, int doc) throws IOException {
+            return source;
+        }
+    }
+
     private SearchHits buildSearchHits(SearchContext context, Profiler profiler) {
 
         FetchContext fetchContext = new FetchContext(context);
@@ -102,6 +112,9 @@ public class FetchPhase {
 
         NestedDocuments nestedDocuments = context.getSearchExecutionContext().getNestedDocuments();
 
+        PreloadedSourceProvider sourceProvider = new PreloadedSourceProvider();
+        context.getSearchExecutionContext().setSourceProvider(sourceProvider);
+
         FetchPhaseDocsIterator docsIterator = new FetchPhaseDocsIterator() {
 
             LeafReaderContext ctx;
@@ -137,6 +150,7 @@ public class FetchPhase {
                     ctx,
                     leafSourceLoader
                 );
+                sourceProvider.source = hit.source();
                 for (FetchSubPhaseProcessor processor : processors) {
                     processor.process(hit);
                 }
@@ -187,15 +201,7 @@ public class FetchPhase {
         SourceLoader.Leaf sourceLoader
     ) throws IOException {
         if (nestedDocuments.advance(docId - subReaderContext.docBase) == null) {
-            return prepareNonNestedHitContext(
-                context,
-                requiresSource,
-                profiler,
-                leafStoredFieldLoader,
-                docId,
-                subReaderContext,
-                sourceLoader
-            );
+            return prepareNonNestedHitContext(requiresSource, profiler, leafStoredFieldLoader, docId, subReaderContext, sourceLoader);
         } else {
             return prepareNestedHitContext(
                 context,
@@ -217,7 +223,6 @@ public class FetchPhase {
      *     allows fetch subphases that use the hit context to access the preloaded source.
      */
     private static HitContext prepareNonNestedHitContext(
-        SearchContext context,
         boolean requiresSource,
         Profiler profiler,
         LeafStoredFieldLoader leafStoredFieldLoader,
@@ -240,9 +245,6 @@ public class FetchPhase {
                 try {
                     profiler.startLoadingSource();
                     source = sourceLoader.source(leafStoredFieldLoader, subDocId);
-                    SourceLookup scriptSourceLookup = context.getSearchExecutionContext().lookup().source();
-                    scriptSourceLookup.setSegmentAndDocument(subReaderContext, subDocId);
-                    scriptSourceLookup.setSourceProvider(new SourceLookup.BytesSourceProvider(source.internalSourceRef()));
                 } finally {
                     profiler.stopLoadingSource();
                 }

server/src/main/java/org/elasticsearch/search/lookup/LeafSearchLookup.java

@@ -10,35 +10,44 @@ package org.elasticsearch.search.lookup;
 
 import org.apache.lucene.index.LeafReaderContext;
 
+import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.util.Map;
+import java.util.function.Supplier;
 
 /**
  * Per-segment version of {@link SearchLookup}.
  */
 public class LeafSearchLookup {
 
-    private final LeafReaderContext ctx;
+    private int doc;
     private final LeafDocLookup docMap;
-    private final SourceLookup sourceLookup;
     private final LeafStoredFieldsLookup fieldsLookup;
     private final Map<String, Object> asMap;
+    private final Supplier<Source> source;
 
-    public LeafSearchLookup(LeafReaderContext ctx, LeafDocLookup docMap, SourceLookup sourceLookup, LeafStoredFieldsLookup fieldsLookup) {
-        this.ctx = ctx;
+    public LeafSearchLookup(
+        LeafReaderContext ctx,
+        LeafDocLookup docMap,
+        SourceProvider sourceProvider,
+        LeafStoredFieldsLookup fieldsLookup
+    ) {
         this.docMap = docMap;
-        this.sourceLookup = sourceLookup;
         this.fieldsLookup = fieldsLookup;
-        this.asMap = Map.of("doc", docMap, "_doc", docMap, "_source", sourceLookup, "_fields", fieldsLookup);
+        this.source = () -> {
+            try {
+                return sourceProvider.getSource(ctx, doc);
+            } catch (IOException e) {
+                throw new UncheckedIOException("Couldn't load source", e);
+            }
+        };
+        this.asMap = Map.of("doc", docMap, "_doc", docMap, "_source", source, "_fields", fieldsLookup);
     }
 
     public Map<String, Object> asMap() {
         return this.asMap;
     }
 
-    public SourceLookup source() {
-        return this.sourceLookup;
-    }
-
     public LeafStoredFieldsLookup fields() {
         return this.fieldsLookup;
     }
@@ -47,9 +56,13 @@ public class LeafSearchLookup {
         return this.docMap;
     }
 
+    public Supplier<Source> source() {
+        return this.source;
+    }
+
     public void setDocument(int docId) {
+        this.doc = docId;
         docMap.setDocument(docId);
-        sourceLookup.setSegmentAndDocument(ctx, docId);
         fieldsLookup.setDocument(docId);
     }
 }

server/src/main/java/org/elasticsearch/search/lookup/SearchLookup.java

@@ -13,6 +13,7 @@ import org.elasticsearch.common.TriFunction;
 import org.elasticsearch.index.fielddata.IndexFieldData;
 import org.elasticsearch.index.mapper.MappedFieldType;
 
+import java.io.IOException;
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Objects;
@@ -20,7 +21,7 @@ import java.util.Set;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
-public class SearchLookup {
+public class SearchLookup implements SourceProvider {
     /**
      * The maximum depth of field dependencies.
      * When a runtime field's doc values depends on another runtime field's doc values,
@@ -39,7 +40,7 @@ public class SearchLookup {
      * {@code b}'s chain will contain {@code ["a", "b"]}.
      */
     private final Set<String> fieldChain;
-    private final SourceLookup sourceLookup;
+    private final SourceProvider sourceProvider;
     private final Function<String, MappedFieldType> fieldTypeLookup;
     private final TriFunction<
         MappedFieldType,
@@ -54,11 +55,11 @@ public class SearchLookup {
     public SearchLookup(
         Function<String, MappedFieldType> fieldTypeLookup,
         TriFunction<MappedFieldType, Supplier<SearchLookup>, MappedFieldType.FielddataOperation, IndexFieldData<?>> fieldDataLookup,
-        SourceLookup.SourceProvider sourceProvider
+        SourceProvider sourceProvider
     ) {
         this.fieldTypeLookup = fieldTypeLookup;
         this.fieldChain = Collections.emptySet();
-        this.sourceLookup = new SourceLookup(sourceProvider);
+        this.sourceProvider = sourceProvider;
         this.fieldDataLookup = fieldDataLookup;
     }
 
@@ -71,7 +72,7 @@ public class SearchLookup {
      */
     private SearchLookup(SearchLookup searchLookup, Set<String> fieldChain) {
         this.fieldChain = Collections.unmodifiableSet(fieldChain);
-        this.sourceLookup = searchLookup.sourceLookup;
+        this.sourceProvider = searchLookup.sourceProvider;
         this.fieldTypeLookup = searchLookup.fieldTypeLookup;
         this.fieldDataLookup = searchLookup.fieldDataLookup;
     }
@@ -101,7 +102,7 @@ public class SearchLookup {
         return new LeafSearchLookup(
             context,
             new LeafDocLookup(fieldTypeLookup, this::getForField, context),
-            sourceLookup,
+            sourceProvider,
             new LeafStoredFieldsLookup(fieldTypeLookup, (doc, visitor) -> context.reader().document(doc, visitor))
         );
     }
@@ -114,7 +115,8 @@ public class SearchLookup {
         return fieldDataLookup.apply(fieldType, () -> forkAndTrackFieldReferences(fieldType.name()), options);
     }
 
-    public SourceLookup source() {
-        return sourceLookup;
+    @Override
+    public Source getSource(LeafReaderContext ctx, int doc) throws IOException {
+        return sourceProvider.getSource(ctx, doc);
     }
 }

server/src/main/java/org/elasticsearch/search/lookup/SourceLookup.java

@@ -1,426 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0 and the Server Side Public License, v 1; you may not use this file except
- * in compliance with, at your election, the Elastic License 2.0 or the Server
- * Side Public License, v 1.
- */
-package org.elasticsearch.search.lookup;
-
-import org.apache.lucene.codecs.StoredFieldsReader;
-import org.apache.lucene.index.LeafReader;
-import org.apache.lucene.index.LeafReaderContext;
-import org.elasticsearch.ElasticsearchParseException;
-import org.elasticsearch.common.CheckedBiConsumer;
-import org.elasticsearch.common.bytes.BytesReference;
-import org.elasticsearch.common.lucene.index.SequentialStoredFieldsLeafReader;
-import org.elasticsearch.common.xcontent.XContentHelper;
-import org.elasticsearch.common.xcontent.support.XContentMapValues;
-import org.elasticsearch.core.MemoizedSupplier;
-import org.elasticsearch.core.Tuple;
-import org.elasticsearch.index.fieldvisitor.FieldsVisitor;
-import org.elasticsearch.xcontent.XContentType;
-
-import java.io.IOException;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import java.util.function.Supplier;
-
-public class SourceLookup implements Source, Map<String, Object> {
-    private SourceProvider sourceProvider;
-
-    private int docId = -1;
-
-    public SourceLookup(SourceProvider sourceProvider) {
-        this.sourceProvider = sourceProvider;
-    }
-
-    @Override
-    public XContentType sourceContentType() {
-        return sourceProvider.sourceContentType();
-    }
-
-    public int docId() {
-        return docId;
-    }
-
-    @Override
-    public Map<String, Object> source() {
-        return sourceProvider.source();
-    }
-
-    public void setSourceProvider(SourceProvider sourceProvider) {
-        this.sourceProvider = sourceProvider;
-    }
-
-    public void setSegmentAndDocument(LeafReaderContext context, int docId) {
-        sourceProvider.setSegmentAndDocument(context, docId);
-        this.docId = docId;
-    }
-
-    /**
-     * Internal source representation, might be compressed....
-     */
-    @Override
-    public BytesReference internalSourceRef() {
-        return sourceProvider.sourceAsBytes();
-    }
-
-    @Override
-    public Source filter(SourceFilter sourceFilter) {
-        return sourceFilter.filterMap(this);
-    }
-
-    /**
-     * Checks if the source has been deserialized as a {@link Map} of java objects.
-     */
-    public boolean hasSourceAsMap() {
-        return sourceProvider.hasSourceAsMap();
-    }
-
-    /**
-     * Returns the values associated with the path. Those are "low" level values, and it can
-     * handle path expression where an array/list is navigated within.
-     *
-     * This method will:
-     *
-     *  - not cache source if it's not already parsed
-     *  - will only extract the desired values from the compressed source instead of deserializing the whole object
-     *
-     * This is useful when the caller only wants a single value from source and does not care of source is fully parsed and cached
-     * for later use.
-     * @param path The path from which to extract the values from source
-     * @return The list of found values or an empty list if none are found
-     */
-    public List<Object> extractRawValuesWithoutCaching(String path) {
-        return sourceProvider.extractRawValuesWithoutCaching(path);
-    }
-
-    private static Tuple<XContentType, Map<String, Object>> sourceAsMapAndType(BytesReference source) throws ElasticsearchParseException {
-        return XContentHelper.convertToMap(source, false);
-    }
-
-    /**
-     * Get the source as a {@link Map} of java objects.
-     * <p>
-     * Important: This can lose precision on numbers with a decimal point. It
-     * converts numbers like {@code "n": 1234.567} to a {@code double} which
-     * only has 52 bits of precision in the mantissa. This will come up most
-     * frequently when folks write nanosecond precision dates as a decimal
-     * number.
-     */
-    public static Map<String, Object> sourceAsMap(BytesReference source) throws ElasticsearchParseException {
-        return sourceAsMapAndType(source).v2();
-    }
-
-    @Override
-    public Object get(Object key) {
-        return source().get(key);
-    }
-
-    @Override
-    public int size() {
-        return source().size();
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return source().isEmpty();
-    }
-
-    @Override
-    public boolean containsKey(Object key) {
-        return source().containsKey(key);
-    }
-
-    @Override
-    public boolean containsValue(Object value) {
-        return source().containsValue(value);
-    }
-
-    @Override
-    public Set<String> keySet() {
-        return source().keySet();
-    }
-
-    @Override
-    public Collection<Object> values() {
-        return source().values();
-    }
-
-    @Override
-    public Set<Map.Entry<String, Object>> entrySet() {
-        return source().entrySet();
-    }
-
-    @Override
-    public Object put(String key, Object value) {
-        throw new UnsupportedOperationException();
-    }
-
-    @Override
-    public Object remove(Object key) {
-        throw new UnsupportedOperationException();
-    }
-
-    @Override
-    @SuppressWarnings("rawtypes")
-    public void putAll(Map m) {
-        throw new UnsupportedOperationException();
-    }
-
-    @Override
-    public void clear() {
-        throw new UnsupportedOperationException();
-    }
-
-    /**
-     * SourceProvider describes how SourceLookup will access the source.
-     */
-    public interface SourceProvider {
-        Map<String, Object> source();
-
-        XContentType sourceContentType();
-
-        BytesReference sourceAsBytes();
-
-        List<Object> extractRawValuesWithoutCaching(String path);
-
-        boolean hasSourceAsMap();
-
-        void setSegmentAndDocument(LeafReaderContext context, int docId);
-    }
-
-    /**
-     * Null source provider when we expect to be given a real source provider in the future.
-     * Exceptions expected to be primarily seen by scripts attempting to access synthetic source.
-     */
-    public static class NullSourceProvider implements SourceProvider {
-        @Override
-        public Map<String, Object> source() {
-            throw new IllegalArgumentException("no source available");
-        }
-
-        @Override
-        public XContentType sourceContentType() {
-            throw new IllegalArgumentException("no source available");
-        }
-
-        @Override
-        public BytesReference sourceAsBytes() {
-            throw new IllegalArgumentException("no source available");
-        }
-
-        @Override
-        public List<Object> extractRawValuesWithoutCaching(String path) {
-            throw new IllegalArgumentException("no source available");
-        }
-
-        @Override
-        public boolean hasSourceAsMap() {
-            return false;
-        }
-
-        @Override
-        public void setSegmentAndDocument(LeafReaderContext context, int docId) {
-            // nothing to do
-        }
-    }
-
-    /**
-     * Provider for source using a given map and optional content type.
-     */
-    private static class MapSourceProvider implements SourceProvider {
-        private final Map<String, Object> source;
-        private final XContentType sourceContentType;
-
-        private MapSourceProvider(Map<String, Object> source) {
-            this.source = source;
-            this.sourceContentType = XContentType.JSON;
-        }
-
-        @Override
-        public Map<String, Object> source() {
-            return source;
-        }
-
-        @Override
-        public XContentType sourceContentType() {
-            return sourceContentType;
-        }
-
-        @Override
-        public BytesReference sourceAsBytes() {
-            throw new UnsupportedOperationException("source as bytes unavailable - empty or already parsed to map");
-        }
-
-        @Override
-        public List<Object> extractRawValuesWithoutCaching(String path) {
-            return XContentMapValues.extractRawValues(path, source);
-        }
-
-        @Override
-        public boolean hasSourceAsMap() {
-            return true;
-        }
-
-        @Override
-        public void setSegmentAndDocument(LeafReaderContext context, int docId) {
-            //
-        }
-    }
-
-    /**
-     * Provider for source using given source bytes.
-     */
-    public static class BytesSourceProvider implements SourceProvider {
-        private BytesReference sourceAsBytes;
-        private Map<String, Object> source;
-        private XContentType sourceContentType;
-
-        public BytesSourceProvider(BytesReference sourceAsBytes) {
-            this.sourceAsBytes = sourceAsBytes;
-        }
-
-        void parseSource() {
-            Tuple<XContentType, Map<String, Object>> tuple = sourceAsMapAndType(sourceAsBytes);
-            this.source = tuple.v2();
-            this.sourceContentType = tuple.v1();
-        }
-
-        @Override
-        public Map<String, Object> source() {
-            if (source == null) {
-                parseSource();
-            }
-            return source;
-        }
-
-        @Override
-        public XContentType sourceContentType() {
-            if (source == null) {
-                parseSource();
-            }
-            return sourceContentType;
-        }
-
-        @Override
-        public BytesReference sourceAsBytes() {
-            return sourceAsBytes;
-        }
-
-        @Override
-        public List<Object> extractRawValuesWithoutCaching(String path) {
-            if (source != null) {
-                return XContentMapValues.extractRawValues(path, source);
-            }
-            return XContentMapValues.extractRawValues(
-                path,
-                XContentHelper.convertToMap(sourceAsBytes, false, null, Set.of(path), null).v2()
-            );
-        }
-
-        @Override
-        public boolean hasSourceAsMap() {
-            return source != null;
-        }
-
-        @Override
-        public void setSegmentAndDocument(LeafReaderContext context, int docId) {
-            //
-        }
-    }
-
-    /**
-     * Provider for source using a fields visitor.
-     */
-    public static class ReaderSourceProvider implements SourceProvider {
-        private LeafReader reader;
-        private CheckedBiConsumer<Integer, FieldsVisitor, IOException> fieldReader;
-        private int docId = -1;
-
-        private SourceProvider sourceProvider;
-
-        public void setSegmentAndDocument(LeafReaderContext context, int docId) {
-            // if we are called with the same document, don't invalidate source
-            if (this.reader == context.reader() && this.docId == docId) {
-                return;
-            }
-
-            // only reset reader and fieldReader when reader changes
-            if (this.reader != context.reader()) {
-                this.reader = context.reader();
-
-                // All the docs to fetch are adjacent but Lucene stored fields are optimized
-                // for random access and don't optimize for sequential access - except for merging.
-                // So we do a little hack here and pretend we're going to do merges in order to
-                // get better sequential access.
-                if (context.reader()instanceof SequentialStoredFieldsLeafReader lf) {
-                    // Avoid eagerly loading the stored fields reader, since this can be expensive
-                    Supplier<StoredFieldsReader> supplier = new MemoizedSupplier<>(lf::getSequentialStoredFieldsReader);
-                    fieldReader = (d, v) -> supplier.get().visitDocument(d, v);
-                } else {
-                    fieldReader = context.reader()::document;
-                }
-            }
-            this.sourceProvider = null;
-            this.docId = docId;
-        }
-
-        @Override
-        public Map<String, Object> source() {
-            if (sourceProvider == null) {
-                readSourceBytes();
-            }
-            return sourceProvider.source();
-        }
-
-        private void readSourceBytes() {
-            try {
-                FieldsVisitor sourceFieldVisitor = new FieldsVisitor(true);
-                fieldReader.accept(docId, sourceFieldVisitor);
-                BytesReference sourceAsBytes = sourceFieldVisitor.source();
-                if (sourceAsBytes == null) {
-                    sourceProvider = new MapSourceProvider(Collections.emptyMap());
-                } else {
-                    sourceProvider = new BytesSourceProvider(sourceAsBytes);
-                    ((BytesSourceProvider) sourceProvider).parseSource();
-                }
-            } catch (Exception e) {
-                throw new ElasticsearchParseException("failed to parse / load source", e);
-            }
-        }
-
-        @Override
-        public XContentType sourceContentType() {
-            if (sourceProvider == null) {
-                readSourceBytes();
-            }
-            return sourceProvider.sourceContentType();
-        }
-
-        @Override
-        public BytesReference sourceAsBytes() {
-            if (sourceProvider == null) {
-                readSourceBytes();
-            }
-            return sourceProvider.sourceAsBytes();
-        }
-
-        @Override
-        public List<Object> extractRawValuesWithoutCaching(String path) {
-            if (sourceProvider == null) {
-                readSourceBytes();
-            }
-            return sourceProvider.extractRawValuesWithoutCaching(path);
-        }
-
-        @Override
-        public boolean hasSourceAsMap() {
-            return sourceProvider != null && sourceProvider.hasSourceAsMap();
-        }
-    }
-}

server/src/main/java/org/elasticsearch/search/lookup/SourceProvider.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.search.lookup;
+
+import org.apache.lucene.index.LeafReaderContext;
+import org.elasticsearch.index.fieldvisitor.LeafStoredFieldLoader;
+import org.elasticsearch.index.fieldvisitor.StoredFieldLoader;
+
+import java.io.IOException;
+
+/**
+ * Provides access to the Source of a document
+ */
+public interface SourceProvider {
+
+    /**
+     * Get the Source for the given doc within the given context
+     */
+    Source getSource(LeafReaderContext ctx, int doc) throws IOException;
+
+    /**
+     * A SourceProvider that loads source from stored fields
+     */
+    static SourceProvider fromStoredFields() {
+        StoredFieldLoader storedFieldLoader = StoredFieldLoader.sequentialSource();
+        return new SourceProvider() {
+
+            // TODO we can make this segment thread safe by keeping an array of LeafStoredFieldLoader/doc/Source
+            // records, indexed by the ordinal of the LeafReaderContext
+
+            LeafReaderContext ctx;
+            int doc;
+            LeafStoredFieldLoader leafStoredFieldLoader;
+            Source source;
+
+            @Override
+            public Source getSource(LeafReaderContext ctx, int doc) throws IOException {
+                if (this.ctx == ctx) {
+                    if (this.doc == doc) {
+                        return source;
+                    }
+                } else {
+                    leafStoredFieldLoader = storedFieldLoader.getLoader(ctx, null);
+                }
+                this.ctx = ctx;
+                this.doc = doc;
+                leafStoredFieldLoader.advanceTo(doc);
+                return source = Source.fromBytes(leafStoredFieldLoader.source());
+            }
+        };
+    }
+}

server/src/test/java/org/elasticsearch/index/fielddata/IndexFieldDataServiceTests.java

@@ -40,7 +40,6 @@ import org.elasticsearch.indices.fielddata.cache.IndicesFieldDataCache;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.script.ScriptCompiler;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESSingleNodeTestCase;
 import org.elasticsearch.test.IndexSettingsModule;
 import org.elasticsearch.test.InternalSettingsPlugin;
@@ -139,7 +138,7 @@ public class IndexFieldDataServiceTests extends ESSingleNodeTestCase {
             searchLookupSetOnce.set(fdc.lookupSupplier());
             return (IndexFieldData.Builder) (cache, breakerService) -> null;
         });
-        SearchLookup searchLookup = new SearchLookup(null, null, new SourceLookup.ReaderSourceProvider());
+        SearchLookup searchLookup = new SearchLookup(null, null, (ctx, doc) -> null);
         ifdService.getForField(ft, new FieldDataContext("qualified", () -> searchLookup, null, MappedFieldType.FielddataOperation.SEARCH));
         assertSame(searchLookup, searchLookupSetOnce.get().get());
     }

server/src/test/java/org/elasticsearch/index/fielddata/SourceValueFetcherIndexFieldDataTests.java

@@ -8,9 +8,7 @@
 
 package org.elasticsearch.index.fielddata;
 
-import org.apache.lucene.index.LeafReaderContext;
 import org.elasticsearch.index.fielddata.SourceValueFetcherSortedBooleanIndexFieldData.SourceValueFetcherSortedBooleanDocValues;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -29,12 +27,7 @@ public class SourceValueFetcherIndexFieldDataTests extends ESTestCase {
         SourceValueFetcherSortedBooleanDocValues values = new SourceValueFetcherSortedBooleanDocValues(
             null,
             (source, doc, ignoredValues) -> docs.get(doc),
-            new SourceLookup(null) {
-                @Override
-                public void setSegmentAndDocument(LeafReaderContext context, int docId) {
-                    // do nothing
-                }
-            }
+            (ctx, doc) -> null
         );
 
         for (int doc = 0; doc < docs.size(); ++doc) {

server/src/test/java/org/elasticsearch/index/mapper/AbstractScriptFieldTypeTestCase.java

@@ -11,6 +11,7 @@ package org.elasticsearch.index.mapper;
 import org.apache.lucene.document.StoredField;
 import org.apache.lucene.index.DirectoryReader;
 import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.store.Directory;
@@ -36,7 +37,7 @@ import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.script.StringFieldScript;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.ToXContent;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentFactory;
@@ -258,13 +259,13 @@ public abstract class AbstractScriptFieldTypeTestCase extends MapperServiceTestC
     }
 
     protected static SearchExecutionContext mockContext(boolean allowExpensiveQueries, MappedFieldType mappedFieldType) {
-        return mockContext(allowExpensiveQueries, mappedFieldType, new SourceLookup.ReaderSourceProvider());
+        return mockContext(allowExpensiveQueries, mappedFieldType, SourceProvider.fromStoredFields());
     }
 
     protected static SearchExecutionContext mockContext(
         boolean allowExpensiveQueries,
         MappedFieldType mappedFieldType,
-        SourceLookup.SourceProvider sourceProvider
+        SourceProvider sourceProvider
     ) {
         SearchExecutionContext context = mock(SearchExecutionContext.class);
         if (mappedFieldType != null) {
@@ -453,7 +454,7 @@ public abstract class AbstractScriptFieldTypeTestCase extends MapperServiceTestC
 
     /**
      * We need to make sure we don't randomize the useThreads parameter for subtests of this abstract test case
-     * because scripted fields use {@link SourceLookup} which isn't thread-safe.
+     * because scripted fields use {@link SearchLookup#getSource(LeafReaderContext, int)} which isn't thread-safe.
      * Also Elasticsearch doesn't support concurrent searches so far, so we don't need to test it.
      */
     protected IndexSearcher newUnthreadedSearcher(IndexReader reader) {

server/src/test/java/org/elasticsearch/index/mapper/BooleanFieldScriptTests.java

@@ -17,7 +17,6 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.BooleanFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 
 import java.io.IOException;
 import java.util.List;
@@ -59,7 +58,7 @@ public class BooleanFieldScriptTests extends FieldScriptTestCase<BooleanFieldScr
                 BooleanFieldScript script = new BooleanFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {

server/src/test/java/org/elasticsearch/index/mapper/BooleanScriptFieldTypeTests.java

@@ -427,8 +427,10 @@ public class BooleanScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeT
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit((Boolean) foo);
                     }
                 }
@@ -441,8 +443,10 @@ public class BooleanScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeT
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit((Boolean) foo ^ ((Boolean) getParams().get("param")));
                     }
                 }

server/src/test/java/org/elasticsearch/index/mapper/CompositeRuntimeFieldTests.java

@@ -16,7 +16,7 @@ import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentType;
 
@@ -345,7 +345,7 @@ public class CompositeRuntimeFieldTests extends MapperServiceTestCase {
                 (mft, lookupSupplier, fdo) -> mft.fielddataBuilder(
                     new FieldDataContext("test", lookupSupplier, mapperService.mappingLookup()::sourcePaths, fdo)
                 ).build(null, null),
-                new SourceLookup.ReaderSourceProvider()
+                SourceProvider.fromStoredFields()
             );
 
             LeafSearchLookup leafSearchLookup = searchLookup.getLeafSearchLookup(reader.leaves().get(0));

server/src/test/java/org/elasticsearch/index/mapper/DateFieldScriptTests.java

@@ -19,7 +19,7 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.DateFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.json.JsonXContent;
 
@@ -68,7 +68,7 @@ public class DateFieldScriptTests extends FieldScriptTestCase<DateFieldScript.Fa
                 DateFieldScript script = new DateFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     DateFormatter.forPattern(randomDateFormatterPattern()).withLocale(randomLocale(random())),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
@@ -105,7 +105,7 @@ public class DateFieldScriptTests extends FieldScriptTestCase<DateFieldScript.Fa
                 DateFieldScript.LeafFactory leafFactory = fromSource().newFactory(
                     "field",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, SourceProvider.fromStoredFields()),
                     DateFormatter.forPattern("epoch_millis"),
                     OnScriptError.FAIL
                 );

server/src/test/java/org/elasticsearch/index/mapper/DateScriptFieldTypeTests.java

@@ -499,8 +499,10 @@ public class DateScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTest
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object timestamp : (List<?>) lookup.source().source().get("timestamp")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object timestamp : (List<?>) source.get("timestamp")) {
                         Parse parse = new Parse(this);
                         emit(parse.parse(timestamp));
                     }
@@ -515,8 +517,10 @@ public class DateScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTest
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object timestamp : (List<?>) lookup.source().source().get("timestamp")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object timestamp : (List<?>) source.get("timestamp")) {
                         long epoch = (Long) timestamp;
                         ZonedDateTime dt = ZonedDateTime.ofInstant(Instant.ofEpochMilli(epoch), ZoneId.of("UTC"));
                         dt = dt.plus(((Number) params.get("days")).longValue(), ChronoUnit.DAYS);

server/src/test/java/org/elasticsearch/index/mapper/DoubleFieldScriptTests.java

@@ -18,7 +18,7 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.DoubleFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.json.JsonXContent;
 
@@ -66,7 +66,7 @@ public class DoubleFieldScriptTests extends FieldScriptTestCase<DoubleFieldScrip
                 DoubleFieldScript script = new DoubleFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -102,7 +102,7 @@ public class DoubleFieldScriptTests extends FieldScriptTestCase<DoubleFieldScrip
                 DoubleFieldScript.LeafFactory leafFactory = fromSource().newFactory(
                     "field",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, SourceProvider.fromStoredFields()),
                     OnScriptError.FAIL
                 );
                 DoubleFieldScript doubleFieldScript = leafFactory.newInstance(reader.leaves().get(0));

server/src/test/java/org/elasticsearch/index/mapper/DoubleScriptFieldTypeTests.java

@@ -254,8 +254,10 @@ public class DoubleScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTe
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit(((Number) foo).doubleValue());
                     }
                 }
@@ -268,8 +270,10 @@ public class DoubleScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTe
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit(((Number) foo).doubleValue() + ((Number) getParams().get("param")).doubleValue());
                     }
                 }

server/src/test/java/org/elasticsearch/index/mapper/GeoPointFieldScriptTests.java

@@ -17,7 +17,6 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.GeoPointFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 
 import java.io.IOException;
 import java.util.List;
@@ -61,7 +60,7 @@ public class GeoPointFieldScriptTests extends FieldScriptTestCase<GeoPointFieldS
                 GeoPointFieldScript script = new GeoPointFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {

server/src/test/java/org/elasticsearch/index/mapper/GeoPointScriptFieldTypeTests.java

@@ -35,6 +35,7 @@ import org.elasticsearch.script.ScoreScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptType;
 import org.elasticsearch.search.MultiValueMode;
+import org.elasticsearch.search.lookup.Source;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -109,16 +110,16 @@ public class GeoPointScriptFieldTypeTests extends AbstractNonTextScriptFieldType
                 {"foo": {"lat": 45.0, "lon" : 45.0}}"""))));
             try (DirectoryReader reader = iw.getReader()) {
                 SearchExecutionContext searchContext = mockContext(true, simpleMappedFieldType());
-                searchContext.lookup().source().setSegmentAndDocument(reader.leaves().get(0), 0);
+                Source source = searchContext.lookup().getSource(reader.leaves().get(0), 0);
                 ValueFetcher fetcher = simpleMappedFieldType().valueFetcher(searchContext, randomBoolean() ? null : "geojson");
                 fetcher.setNextReader(reader.leaves().get(0));
                 assertThat(
-                    fetcher.fetchValues(searchContext.lookup().source(), 0, null),
+                    fetcher.fetchValues(source, 0, null),
                     equalTo(List.of(Map.of("type", "Point", "coordinates", List.of(45.0, 45.0))))
                 );
                 fetcher = simpleMappedFieldType().valueFetcher(searchContext, "wkt");
                 fetcher.setNextReader(reader.leaves().get(0));
-                assertThat(fetcher.fetchValues(searchContext.lookup().source(), 0, null), equalTo(List.of("POINT (45.0 45.0)")));
+                assertThat(fetcher.fetchValues(source, 0, null), equalTo(List.of("POINT (45.0 45.0)")));
             }
         }
     }
@@ -241,8 +242,10 @@ public class GeoPointScriptFieldTypeTests extends AbstractNonTextScriptFieldType
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    Map<?, ?> foo = (Map<?, ?>) lookup.source().source().get("foo");
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    Map<?, ?> foo = (Map<?, ?>) source.get("foo");
                     emit(((Number) foo.get("lat")).doubleValue(), ((Number) foo.get("lon")).doubleValue());
                 }
             };

server/src/test/java/org/elasticsearch/index/mapper/IgnoredFieldMapperTests.java

@@ -14,7 +14,8 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.IndexSearcher;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -64,20 +65,15 @@ public class IgnoredFieldMapperTests extends MetadataMapperTestCase {
             mapperService,
             iw -> { iw.addDocument(mapperService.documentMapper().parse(source(b -> b.field("field", "value"))).rootDoc()); },
             iw -> {
-                SearchLookup lookup = new SearchLookup(
-                    mapperService::fieldType,
-                    fieldDataLookup(mapperService),
-                    new SourceLookup.ReaderSourceProvider()
-                );
+                SearchLookup lookup = new SearchLookup(mapperService::fieldType, fieldDataLookup(mapperService), (ctx, doc) -> null);
                 SearchExecutionContext searchExecutionContext = mock(SearchExecutionContext.class);
                 when(searchExecutionContext.lookup()).thenReturn(lookup);
                 IgnoredFieldMapper.IgnoredFieldType ft = (IgnoredFieldMapper.IgnoredFieldType) mapperService.fieldType("_ignored");
                 ValueFetcher valueFetcher = ft.valueFetcher(searchExecutionContext, null);
                 IndexSearcher searcher = newSearcher(iw);
                 LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-                lookup.source().setSegmentAndDocument(context, 0);
                 valueFetcher.setNextReader(context);
-                assertEquals(List.of("field"), valueFetcher.fetchValues(lookup.source(), 0, new ArrayList<>()));
+                assertEquals(List.of("field"), valueFetcher.fetchValues(Source.empty(XContentType.JSON), 0, new ArrayList<>()));
             }
         );
     }

server/src/test/java/org/elasticsearch/index/mapper/IndexFieldMapperTests.java

@@ -12,7 +12,6 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.IndexSearcher;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -60,18 +59,13 @@ public class IndexFieldMapperTests extends MetadataMapperTestCase {
             iw.addDocument(mapperService.documentMapper().parse(source).rootDoc());
         }, iw -> {
             IndexFieldMapper.IndexFieldType ft = (IndexFieldMapper.IndexFieldType) mapperService.fieldType("_index");
-            SearchLookup lookup = new SearchLookup(
-                mapperService::fieldType,
-                fieldDataLookup(mapperService),
-                new SourceLookup.ReaderSourceProvider()
-            );
+            SearchLookup lookup = new SearchLookup(mapperService::fieldType, fieldDataLookup(mapperService), (ctx, doc) -> null);
             SearchExecutionContext searchExecutionContext = createSearchExecutionContext(mapperService);
             ValueFetcher valueFetcher = ft.valueFetcher(searchExecutionContext, null);
             IndexSearcher searcher = newSearcher(iw);
             LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-            lookup.source().setSegmentAndDocument(context, 0);
             valueFetcher.setNextReader(context);
-            assertEquals(List.of(index), valueFetcher.fetchValues(lookup.source(), 0, Collections.emptyList()));
+            assertEquals(List.of(index), valueFetcher.fetchValues(lookup.getSource(context, 0), 0, Collections.emptyList()));
         });
     }
 

server/src/test/java/org/elasticsearch/index/mapper/IpFieldScriptTests.java

@@ -18,7 +18,7 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.IpFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.json.JsonXContent;
 
@@ -67,7 +67,7 @@ public class IpFieldScriptTests extends FieldScriptTestCase<IpFieldScript.Factor
                 IpFieldScript script = new IpFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -103,7 +103,7 @@ public class IpFieldScriptTests extends FieldScriptTestCase<IpFieldScript.Factor
                 IpFieldScript.LeafFactory leafFactory = fromSource().newFactory(
                     "field",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, SourceProvider.fromStoredFields()),
                     OnScriptError.FAIL
                 );
                 IpFieldScript ipFieldScript = leafFactory.newInstance(reader.leaves().get(0));

server/src/test/java/org/elasticsearch/index/mapper/IpScriptFieldTypeTests.java

@@ -268,8 +268,10 @@ public class IpScriptFieldTypeTests extends AbstractScriptFieldTypeTestCase {
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit(foo.toString());
                     }
                 }
@@ -282,8 +284,10 @@ public class IpScriptFieldTypeTests extends AbstractScriptFieldTypeTestCase {
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit(foo.toString() + getParams().get("param"));
                     }
                 }

server/src/test/java/org/elasticsearch/index/mapper/KeywordScriptFieldTypeTests.java

@@ -40,7 +40,6 @@ import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptType;
 import org.elasticsearch.script.StringFieldScript;
 import org.elasticsearch.search.MultiValueMode;
-import org.elasticsearch.search.lookup.SourceLookup;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -293,23 +292,6 @@ public class KeywordScriptFieldTypeTests extends AbstractScriptFieldTypeTestCase
         }
     }
 
-    public void testSyntheticSourceAccess() throws IOException {
-        try (Directory directory = newDirectory(); RandomIndexWriter iw = new RandomIndexWriter(random(), directory)) {
-            iw.addDocument(List.of(new StoredField("_source", new BytesRef("{\"foo\": [1]}"))));
-            iw.addDocument(List.of(new StoredField("_source", new BytesRef("{\"foo\": [2]}"))));
-            try (DirectoryReader reader = iw.getReader()) {
-                IndexSearcher searcher = newUnthreadedSearcher(reader);
-                KeywordScriptFieldType fieldType = build("append_param", Map.of("param", "-suffix"), OnScriptError.FAIL);
-                expectThrows(
-                    IllegalArgumentException.class,
-                    () -> {
-                        searcher.count(fieldType.termQuery("1-suffix", mockContext(true, null, new SourceLookup.NullSourceProvider())));
-                    }
-                );
-            }
-        }
-    }
-
     @Override
     protected Query randomTermQuery(MappedFieldType ft, SearchExecutionContext ctx) {
         return ft.termQuery(randomAlphaOfLengthBetween(1, 1000), ctx);
@@ -413,8 +395,10 @@ public class KeywordScriptFieldTypeTests extends AbstractScriptFieldTypeTestCase
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit(foo.toString());
                     }
                 }
@@ -427,8 +411,10 @@ public class KeywordScriptFieldTypeTests extends AbstractScriptFieldTypeTestCase
                 ctx
             ) {
                 @Override
+                @SuppressWarnings("unchecked")
                 public void execute() {
-                    for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                    Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                    for (Object foo : (List<?>) source.get("foo")) {
                         emit(foo.toString() + getParams().get("param").toString());
                     }
                 }

server/src/test/java/org/elasticsearch/index/mapper/LongFieldScriptTests.java

@@ -18,7 +18,7 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.LongFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.json.JsonXContent;
 
@@ -66,7 +66,7 @@ public class LongFieldScriptTests extends FieldScriptTestCase<LongFieldScript.Fa
                 LongFieldScript script = new LongFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -102,7 +102,7 @@ public class LongFieldScriptTests extends FieldScriptTestCase<LongFieldScript.Fa
                 LongFieldScript.LeafFactory leafFactory = fromSource().newFactory(
                     "field",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, SourceProvider.fromStoredFields()),
                     OnScriptError.FAIL
                 );
                 LongFieldScript longFieldScript = leafFactory.newInstance(reader.leaves().get(0));

server/src/test/java/org/elasticsearch/index/mapper/LongScriptFieldTypeTests.java

@@ -288,8 +288,10 @@ public class LongScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTest
                     ctx
                 ) {
                     @Override
+                    @SuppressWarnings("unchecked")
                     public void execute() {
-                        for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                        Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                        for (Object foo : (List<?>) source.get("foo")) {
                             emit(((Number) foo).longValue());
                         }
                     }
@@ -303,8 +305,10 @@ public class LongScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTest
                     ctx
                 ) {
                     @Override
+                    @SuppressWarnings("unchecked")
                     public void execute() {
-                        for (Object foo : (List<?>) lookup.source().source().get("foo")) {
+                        Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                        for (Object foo : (List<?>) source.get("foo")) {
                             emit(((Number) foo).longValue() + ((Number) getParams().get("param")).longValue());
                         }
                     }
@@ -320,8 +324,10 @@ public class LongScriptFieldTypeTests extends AbstractNonTextScriptFieldTypeTest
                     ctx
                 ) {
                     @Override
+                    @SuppressWarnings("unchecked")
                     public void execute() {
-                        for (Object timestamp : (List<?>) lookup.source().source().get("timestamp")) {
+                        Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                        for (Object timestamp : (List<?>) source.get("timestamp")) {
                             emit(now - ((Number) timestamp).longValue());
                         }
                     }

server/src/test/java/org/elasticsearch/index/mapper/PlaceHolderFieldMapperTests.java

@@ -18,7 +18,8 @@ import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.search.fetch.subphase.FieldAndFormat;
 import org.elasticsearch.search.fetch.subphase.FieldFetcher;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 
 import java.util.Collections;
@@ -65,7 +66,7 @@ public class PlaceHolderFieldMapperTests extends MapperServiceTestCase {
             SearchLookup lookup = new SearchLookup(
                 mapperService::fieldType,
                 fieldDataLookup(mapperService),
-                new SourceLookup.ReaderSourceProvider()
+                SourceProvider.fromStoredFields()
             );
             SearchExecutionContext searchExecutionContext = createSearchExecutionContext(mapperService);
             FieldFetcher fieldFetcher = FieldFetcher.create(
@@ -74,8 +75,8 @@ public class PlaceHolderFieldMapperTests extends MapperServiceTestCase {
             );
             IndexSearcher searcher = newSearcher(iw);
             LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-            lookup.source().setSegmentAndDocument(context, 0);
-            Map<String, DocumentField> fields = fieldFetcher.fetch(lookup.source(), 0);
+            Source source = lookup.getSource(context, 0);
+            Map<String, DocumentField> fields = fieldFetcher.fetch(source, 0);
             assertEquals(1, fields.size());
             assertEquals(List.of("value"), fields.get("field").getValues());
         });

server/src/test/java/org/elasticsearch/index/mapper/ProvidedIdFieldMapperTests.java

@@ -16,7 +16,8 @@ import org.elasticsearch.index.fielddata.FieldDataContext;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -76,7 +77,7 @@ public class ProvidedIdFieldMapperTests extends MapperServiceTestCase {
                 SearchLookup lookup = new SearchLookup(
                     mapperService::fieldType,
                     fieldDataLookup(mapperService),
-                    new SourceLookup.ReaderSourceProvider()
+                    SourceProvider.fromStoredFields()
                 );
                 SearchExecutionContext searchExecutionContext = mock(SearchExecutionContext.class);
                 when(searchExecutionContext.lookup()).thenReturn(lookup);
@@ -84,9 +85,9 @@ public class ProvidedIdFieldMapperTests extends MapperServiceTestCase {
                 ValueFetcher valueFetcher = ft.valueFetcher(searchExecutionContext, null);
                 IndexSearcher searcher = newSearcher(iw);
                 LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-                lookup.source().setSegmentAndDocument(context, 0);
+                Source source = lookup.getSource(context, 0);
                 valueFetcher.setNextReader(context);
-                assertEquals(List.of(id), valueFetcher.fetchValues(lookup.source(), 0, new ArrayList<>()));
+                assertEquals(List.of(id), valueFetcher.fetchValues(source, 0, new ArrayList<>()));
             }
         );
     }

server/src/test/java/org/elasticsearch/index/mapper/RoutingFieldMapperTests.java

@@ -13,7 +13,7 @@ import org.apache.lucene.search.IndexSearcher;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.xcontent.XContentFactory;
 import org.elasticsearch.xcontent.XContentType;
 
@@ -74,20 +74,15 @@ public class RoutingFieldMapperTests extends MetadataMapperTestCase {
             mapperService,
             iw -> { iw.addDocument(mapperService.documentMapper().parse(source("1", b -> {}, "abcd")).rootDoc()); },
             iw -> {
-                SearchLookup lookup = new SearchLookup(
-                    mapperService::fieldType,
-                    fieldDataLookup(mapperService),
-                    new SourceLookup.ReaderSourceProvider()
-                );
+                SearchLookup lookup = new SearchLookup(mapperService::fieldType, fieldDataLookup(mapperService), (ctx, doc) -> null);
                 SearchExecutionContext searchExecutionContext = mock(SearchExecutionContext.class);
                 when(searchExecutionContext.lookup()).thenReturn(lookup);
                 RoutingFieldMapper.RoutingFieldType ft = (RoutingFieldMapper.RoutingFieldType) mapperService.fieldType("_routing");
                 ValueFetcher valueFetcher = ft.valueFetcher(searchExecutionContext, null);
                 IndexSearcher searcher = newSearcher(iw);
                 LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-                lookup.source().setSegmentAndDocument(context, 0);
                 valueFetcher.setNextReader(context);
-                assertEquals(List.of("abcd"), valueFetcher.fetchValues(lookup.source(), 0, new ArrayList<>()));
+                assertEquals(List.of("abcd"), valueFetcher.fetchValues(Source.empty(XContentType.JSON), 0, new ArrayList<>()));
             }
         );
     }

server/src/test/java/org/elasticsearch/index/mapper/StringFieldScriptTests.java

@@ -18,7 +18,7 @@ import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.script.StringFieldScript;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.json.JsonXContent;
 
@@ -65,7 +65,7 @@ public class StringFieldScriptTests extends FieldScriptTestCase<StringFieldScrip
                 StringFieldScript script = new StringFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -92,7 +92,7 @@ public class StringFieldScriptTests extends FieldScriptTestCase<StringFieldScrip
                 StringFieldScript script = new StringFieldScript(
                     "test",
                     Map.of(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -133,7 +133,7 @@ public class StringFieldScriptTests extends FieldScriptTestCase<StringFieldScrip
                 StringFieldScript.LeafFactory leafFactory = fromSource().newFactory(
                     "field",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, SourceProvider.fromStoredFields()),
                     OnScriptError.FAIL
                 );
                 StringFieldScript stringFieldScript = leafFactory.newInstance(reader.leaves().get(0));
@@ -163,7 +163,7 @@ public class StringFieldScriptTests extends FieldScriptTestCase<StringFieldScrip
                 StringFieldScript.LeafFactory leafFactory = fromSource().newFactory(
                     "field",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, fdt) -> null, SourceProvider.fromStoredFields()),
                     OnScriptError.FAIL
                 );
                 StringFieldScript stringFieldScript = leafFactory.newInstance(reader.leaves().get(0));

server/src/test/java/org/elasticsearch/index/mapper/VersionFieldMapperTests.java

@@ -15,7 +15,8 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.IndexSearcher;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -64,18 +65,13 @@ public class VersionFieldMapperTests extends MetadataMapperTestCase {
             iw.addDocument(parsedDoc.rootDoc());
         }, iw -> {
             VersionFieldMapper.VersionFieldType ft = (VersionFieldMapper.VersionFieldType) mapperService.fieldType("_version");
-            SearchLookup lookup = new SearchLookup(
-                mapperService::fieldType,
-                fieldDataLookup(mapperService),
-                new SourceLookup.ReaderSourceProvider()
-            );
+            SearchLookup lookup = new SearchLookup(mapperService::fieldType, fieldDataLookup(mapperService), (ctx, doc) -> null);
             SearchExecutionContext searchExecutionContext = createSearchExecutionContext(mapperService);
             ValueFetcher valueFetcher = ft.valueFetcher(searchExecutionContext, null);
             IndexSearcher searcher = newSearcher(iw);
             LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-            lookup.source().setSegmentAndDocument(context, 0);
             valueFetcher.setNextReader(context);
-            assertEquals(List.of(version), valueFetcher.fetchValues(lookup.source(), 0, Collections.emptyList()));
+            assertEquals(List.of(version), valueFetcher.fetchValues(Source.empty(XContentType.JSON), 0, Collections.emptyList()));
         });
     }
 

server/src/test/java/org/elasticsearch/index/query/SearchExecutionContextTests.java

@@ -25,6 +25,7 @@ import org.apache.lucene.store.Directory;
 import org.apache.lucene.tests.index.RandomIndexWriter;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
+import org.elasticsearch.common.Explicit;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.BigArrays;
@@ -57,6 +58,7 @@ import org.elasticsearch.index.mapper.NumberFieldMapper;
 import org.elasticsearch.index.mapper.ObjectMapper;
 import org.elasticsearch.index.mapper.RootObjectMapper;
 import org.elasticsearch.index.mapper.RuntimeField;
+import org.elasticsearch.index.mapper.SourceFieldMapper;
 import org.elasticsearch.index.mapper.TestRuntimeField;
 import org.elasticsearch.index.mapper.TextFieldMapper;
 import org.elasticsearch.indices.IndicesModule;
@@ -69,10 +71,13 @@ import org.elasticsearch.search.MultiValueMode;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 import org.elasticsearch.search.lookup.LeafDocLookup;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
+import org.elasticsearch.search.lookup.SearchLookup;
+import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.search.sort.BucketedSort;
 import org.elasticsearch.search.sort.SortOrder;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.xcontent.XContentParserConfiguration;
+import org.elasticsearch.xcontent.XContentType;
 import org.mockito.stubbing.Answer;
 
 import java.io.IOException;
@@ -390,6 +395,30 @@ public class SearchExecutionContextTests extends ESTestCase {
         assertTrue(mappingLookup.isMultiField("cat.subfield"));
     }
 
+    public void testSyntheticSourceScriptLoading() throws IOException {
+
+        // Build a mapping using synthetic source
+        SourceFieldMapper sourceMapper = new SourceFieldMapper.Builder().setSynthetic().build();
+        RootObjectMapper root = new RootObjectMapper.Builder("_doc", Explicit.IMPLICIT_TRUE).build(MapperBuilderContext.root(true));
+        Mapping mapping = new Mapping(root, new MetadataFieldMapper[] { sourceMapper }, Map.of());
+        MappingLookup lookup = MappingLookup.fromMapping(mapping);
+
+        SearchExecutionContext sec = createSearchExecutionContext("index", "", lookup, Map.of());
+
+        // Attempting to access synthetic source via this context should throw an error
+        SearchLookup searchLookup = sec.lookup();
+        Exception e = expectThrows(IllegalArgumentException.class, () -> searchLookup.getSource(null, 0));
+        assertThat(e.getMessage(), equalTo("Cannot access source from scripts in synthetic mode"));
+
+        // Setting the source provider explicitly then gives us a new SearchLookup that can use source
+        Source source = Source.fromMap(Map.of("field", "value"), XContentType.JSON);
+        sec.setSourceProvider((ctx, doc) -> source);
+        SearchLookup searchLookup1 = sec.lookup();
+        assertNotSame(searchLookup, searchLookup1);
+        assertSame(source, searchLookup1.getSource(null, 0));
+
+    }
+
     public static SearchExecutionContext createSearchExecutionContext(String indexUuid, String clusterAlias) {
         return createSearchExecutionContext(indexUuid, clusterAlias, MappingLookup.EMPTY, Map.of());
     }

server/src/test/java/org/elasticsearch/script/CompositeFieldScriptTests.java

@@ -15,7 +15,6 @@ import org.apache.lucene.tests.index.RandomIndexWriter;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.index.mapper.OnScriptError;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -33,7 +32,7 @@ public class CompositeFieldScriptTests extends ESTestCase {
                 CompositeFieldScript script = new CompositeFieldScript(
                     "composite",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -65,7 +64,7 @@ public class CompositeFieldScriptTests extends ESTestCase {
                 CompositeFieldScript script = new CompositeFieldScript(
                     "composite",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {
@@ -79,7 +78,7 @@ public class CompositeFieldScriptTests extends ESTestCase {
                 StringFieldScript stringFieldScript = new StringFieldScript(
                     "composite.leaf",
                     Collections.emptyMap(),
-                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, (ctx, doc) -> null),
                     OnScriptError.FAIL,
                     reader.leaves().get(0)
                 ) {

server/src/test/java/org/elasticsearch/script/field/SortedNumericDocValuesLongFieldScriptTests.java

@@ -18,7 +18,6 @@ import org.apache.lucene.tests.index.RandomIndexWriter;
 import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.SortedNumericDocValuesLongFieldScript;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -40,7 +39,7 @@ public class SortedNumericDocValuesLongFieldScriptTests extends ESTestCase {
             try (DirectoryReader reader = iw.getReader()) {
                 SortedNumericDocValuesLongFieldScript docValues = new SortedNumericDocValuesLongFieldScript(
                     "test",
-                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, (ctx, doc) -> null),
                     reader.leaves().get(0)
                 );
                 List<Long> values = new ArrayList<>();

server/src/test/java/org/elasticsearch/script/field/SortedSetDocValuesStringFieldScriptTests.java

@@ -19,7 +19,6 @@ import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.script.AbstractFieldScript;
 import org.elasticsearch.script.SortedSetDocValuesStringFieldScript;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -41,7 +40,7 @@ public class SortedSetDocValuesStringFieldScriptTests extends ESTestCase {
             try (DirectoryReader reader = iw.getReader()) {
                 SortedSetDocValuesStringFieldScript docValues = new SortedSetDocValuesStringFieldScript(
                     "test",
-                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, new SourceLookup.ReaderSourceProvider()),
+                    new SearchLookup(field -> null, (ft, lookup, ftd) -> null, (ctx, doc) -> null),
                     reader.leaves().get(0)
                 );
                 List<String> values = new ArrayList<>();

server/src/test/java/org/elasticsearch/search/aggregations/bucket/range/RangeAggregatorTests.java

@@ -36,7 +36,6 @@ import org.elasticsearch.search.aggregations.AggregatorTestCase;
 import org.elasticsearch.search.aggregations.CardinalityUpperBound;
 import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.search.runtime.StringScriptFieldTermQuery;
 
 import java.io.IOException;
@@ -599,7 +598,7 @@ public class RangeAggregatorTests extends AggregatorTestCase {
      */
     public void testRuntimeFieldTopLevelQueryNotOptimized() throws IOException {
         long totalDocs = (long) RangeAggregator.DOCS_PER_RANGE_TO_USE_FILTERS * 4;
-        SearchLookup lookup = new SearchLookup(s -> null, (ft, l, ftd) -> null, new SourceLookup.ReaderSourceProvider());
+        SearchLookup lookup = new SearchLookup(s -> null, (ft, l, ftd) -> null, (ctx, doc) -> null);
         StringFieldScript.LeafFactory scriptFactory = ctx -> new StringFieldScript("dummy", Map.of(), lookup, OnScriptError.FAIL, ctx) {
             @Override
             public void execute() {

server/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorTests.java

@@ -114,7 +114,6 @@ import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
 import org.elasticsearch.search.aggregations.support.ValueType;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.search.runtime.StringScriptFieldTermQuery;
 import org.elasticsearch.search.sort.FieldSortBuilder;
 import org.elasticsearch.search.sort.ScoreSortBuilder;
@@ -1995,7 +1994,7 @@ public class TermsAggregatorTests extends AggregatorTestCase {
      */
     public void testRuntimeFieldTopLevelNotOptimized() throws IOException {
         long totalDocs = 500;
-        SearchLookup lookup = new SearchLookup(s -> null, (ft, l, ftd) -> null, new SourceLookup.ReaderSourceProvider());
+        SearchLookup lookup = new SearchLookup(s -> null, (ft, l, ftd) -> null, (ctx, doc) -> null);
         StringFieldScript.LeafFactory scriptFactory = ctx -> new StringFieldScript("dummy", Map.of(), lookup, OnScriptError.FAIL, ctx) {
             @Override
             public void execute() {

server/src/test/java/org/elasticsearch/search/aggregations/support/ScriptValuesTests.java

@@ -19,7 +19,6 @@ import org.elasticsearch.search.aggregations.support.values.ScriptDoubleValues;
 import org.elasticsearch.search.aggregations.support.values.ScriptLongValues;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -37,7 +36,7 @@ public class ScriptValuesTests extends ESTestCase {
         int index;
 
         FakeAggregationScript(Object[][] values) {
-            super(Collections.emptyMap(), new SearchLookup(null, null, new SourceLookup.ReaderSourceProvider()) {
+            super(Collections.emptyMap(), new SearchLookup(null, null, (ctx, doc) -> null) {
 
                 @Override
                 public LeafSearchLookup getLeafSearchLookup(LeafReaderContext context) {

server/src/test/java/org/elasticsearch/search/fetch/subphase/FieldFetcherTests.java

@@ -35,7 +35,7 @@ import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.Source;
 import org.elasticsearch.search.lookup.SourceFilter;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentFactory;
 import org.elasticsearch.xcontent.XContentType;
@@ -247,10 +247,9 @@ public class FieldFetcherTests extends MapperServiceTestCase {
             LeafReaderContext readerContext = searcher.getIndexReader().leaves().get(0);
             fieldFetcher.setNextReader(readerContext);
 
-            SourceLookup sourceLookup = new SourceLookup(new SourceLookup.ReaderSourceProvider());
-            sourceLookup.setSegmentAndDocument(readerContext, 0);
+            Source s = SourceProvider.fromStoredFields().getSource(readerContext, 0);
 
-            Map<String, DocumentField> fetchedFields = fieldFetcher.fetch(sourceLookup, 0);
+            Map<String, DocumentField> fetchedFields = fieldFetcher.fetch(s, 0);
             assertThat(fetchedFields.size(), equalTo(5));
             assertEquals(docId, fetchedFields.get("_id").getValue());
             assertEquals(routing, fetchedFields.get("_routing").getValue());
@@ -1143,7 +1142,8 @@ public class FieldFetcherTests extends MapperServiceTestCase {
             IndexSearcher searcher = newSearcher(iw);
             LeafReaderContext readerContext = searcher.getIndexReader().leaves().get(0);
             fieldFetcher.setNextReader(readerContext);
-            Map<String, DocumentField> fields = fieldFetcher.fetch(new SourceLookup(new SourceLookup.ReaderSourceProvider()), 0);
+            Source source = SourceProvider.fromStoredFields().getSource(readerContext, 0);
+            Map<String, DocumentField> fields = fieldFetcher.fetch(source, 0);
             assertEquals(1, fields.size());
             DocumentField field = fields.get("runtime_field");
             assertEquals(1L, (long) field.getValue());
@@ -1175,9 +1175,7 @@ public class FieldFetcherTests extends MapperServiceTestCase {
             IndexSearcher searcher = newSearcher(iw);
             LeafReaderContext readerContext = searcher.getIndexReader().leaves().get(0);
             fieldFetcher.setNextReader(readerContext);
-            SourceLookup sourceLookup = new SourceLookup(new SourceLookup.ReaderSourceProvider());
-            sourceLookup.setSegmentAndDocument(readerContext, 0);
-            Map<String, DocumentField> fields = fieldFetcher.fetch(sourceLookup, 0);
+            Map<String, DocumentField> fields = fieldFetcher.fetch(Source.empty(XContentType.JSON), 0);
             assertEquals(1, fields.size());
             DocumentField field = fields.get("_id");
             assertEquals("1", field.getValue());

server/src/test/java/org/elasticsearch/search/lookup/SourceLookupTests.java

@@ -1,77 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the Elastic License
- * 2.0 and the Server Side Public License, v 1; you may not use this file except
- * in compliance with, at your election, the Elastic License 2.0 or the Server
- * Side Public License, v 1.
- */
-
-package org.elasticsearch.search.lookup;
-
-import org.apache.lucene.codecs.StoredFieldsReader;
-import org.apache.lucene.document.Document;
-import org.apache.lucene.document.Field;
-import org.apache.lucene.document.StoredField;
-import org.apache.lucene.document.StringField;
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.index.LeafReader;
-import org.apache.lucene.index.LeafReaderContext;
-import org.apache.lucene.store.Directory;
-import org.apache.lucene.tests.index.RandomIndexWriter;
-import org.apache.lucene.util.BytesRef;
-import org.elasticsearch.ElasticsearchParseException;
-import org.elasticsearch.common.lucene.index.SequentialStoredFieldsLeafReader;
-import org.elasticsearch.test.ESTestCase;
-
-import java.io.IOException;
-
-import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.instanceOf;
-
-public class SourceLookupTests extends ESTestCase {
-
-    public void testSetSegmentAndDocument() throws IOException {
-        try (Directory dir = newDirectory(); RandomIndexWriter iw = new RandomIndexWriter(random(), dir)) {
-            Document doc = new Document();
-            doc.add(new StringField("field", "value", Field.Store.YES));
-            doc.add(new StoredField("_source", new BytesRef("{\"field\": \"value\"}")));
-            iw.addDocument(doc);
-
-            try (IndexReader reader = iw.getReader()) {
-                LeafReaderContext readerContext = reader.leaves().get(0);
-
-                SourceLookup sourceLookup = new SourceLookup(new SourceLookup.ReaderSourceProvider());
-                sourceLookup.setSegmentAndDocument(readerContext, 0);
-                sourceLookup.source();
-                assertNotNull(sourceLookup.internalSourceRef());
-
-                // Source should be preserved if we pass in the same reader and document
-                sourceLookup.setSegmentAndDocument(readerContext, 0);
-                assertNotNull(sourceLookup.internalSourceRef());
-
-                // Check that the stored fields reader is not loaded eagerly
-                LeafReader throwingReader = new SequentialStoredFieldsLeafReader(readerContext.reader()) {
-                    @Override
-                    protected StoredFieldsReader doGetSequentialStoredFieldsReader(StoredFieldsReader reader) {
-                        throw new UnsupportedOperationException("attempted to load stored fields reader");
-                    }
-
-                    @Override
-                    public CacheHelper getReaderCacheHelper() {
-                        return in.getReaderCacheHelper();
-                    }
-
-                    @Override
-                    public CacheHelper getCoreCacheHelper() {
-                        return in.getCoreCacheHelper();
-                    }
-                };
-
-                sourceLookup.setSegmentAndDocument(throwingReader.getContext(), 0);
-                ElasticsearchParseException e = expectThrows(ElasticsearchParseException.class, sourceLookup::source);
-                assertThat(e.getCause(), instanceOf(UnsupportedOperationException.class));
-                assertThat(e.getCause().getMessage(), containsString("attempted to load stored fields reader"));
-            }
-        }
-    }
-}

server/src/test/java/org/elasticsearch/search/lookup/SourceProviderTests.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.search.lookup;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.StoredField;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.tests.index.RandomIndexWriter;
+import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.test.ESTestCase;
+
+import java.io.IOException;
+
+public class SourceProviderTests extends ESTestCase {
+
+    public void testStoredFieldsSourceProvider() throws IOException {
+        try (Directory dir = newDirectory(); RandomIndexWriter iw = new RandomIndexWriter(random(), dir)) {
+            Document doc = new Document();
+            doc.add(new StringField("field", "value", Field.Store.YES));
+            doc.add(new StoredField("_source", new BytesRef("{\"field\": \"value\"}")));
+            iw.addDocument(doc);
+
+            try (IndexReader reader = iw.getReader()) {
+                LeafReaderContext readerContext = reader.leaves().get(0);
+
+                SourceProvider sourceProvider = SourceProvider.fromStoredFields();
+                Source source = sourceProvider.getSource(readerContext, 0);
+
+                assertNotNull(source.internalSourceRef());
+
+                // Source should be preserved if we pass in the same reader and document
+                Source s2 = sourceProvider.getSource(readerContext, 0);
+                assertSame(s2, source);
+            }
+        }
+    }
+}

server/src/test/java/org/elasticsearch/search/query/ScriptScoreQueryTests.java

@@ -28,7 +28,6 @@ import org.elasticsearch.script.ScoreScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 import org.junit.After;
 import org.junit.Before;
@@ -50,7 +49,7 @@ public class ScriptScoreQueryTests extends ESTestCase {
     private DirectoryReader reader;
     private IndexSearcher searcher;
     private LeafReaderContext leafReaderContext;
-    private final SearchLookup lookup = new SearchLookup(null, null, new SourceLookup.ReaderSourceProvider());
+    private final SearchLookup lookup = new SearchLookup(null, null, (ctx, doc) -> null);
 
     @Before
     public void initSearcher() throws IOException {
@@ -179,7 +178,7 @@ public class ScriptScoreQueryTests extends ESTestCase {
             }
 
             @Override
-            public ScoreScript newInstance(DocReader docReader) throws IOException {
+            public ScoreScript newInstance(DocReader docReader) {
                 return new ScoreScript(script.getParams(), lookup, docReader) {
                     @Override
                     public double execute(ExplanationHolder explanation) {

server/src/test/java/org/elasticsearch/search/runtime/GeoPointScriptFieldDistanceFeatureQueryTests.java

@@ -26,7 +26,7 @@ import org.elasticsearch.script.AbstractLongFieldScript;
 import org.elasticsearch.script.GeoPointFieldScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.List;
@@ -84,7 +84,7 @@ public class GeoPointScriptFieldDistanceFeatureQueryTests extends AbstractScript
             iw.addDocument(List.of(new StoredField("_source", new BytesRef("{\"location\": [-3.56, -45.98]}"))));
             try (DirectoryReader reader = iw.getReader()) {
                 IndexSearcher searcher = newSearcher(reader);
-                SearchLookup searchLookup = new SearchLookup(null, null, new SourceLookup.ReaderSourceProvider());
+                SearchLookup searchLookup = new SearchLookup(null, null, SourceProvider.fromStoredFields());
                 Function<LeafReaderContext, GeoPointFieldScript> leafFactory = ctx -> new GeoPointFieldScript(
                     "test",
                     Map.of(),
@@ -93,8 +93,10 @@ public class GeoPointScriptFieldDistanceFeatureQueryTests extends AbstractScript
                     ctx
                 ) {
                     @Override
+                    @SuppressWarnings("unchecked")
                     public void execute() {
-                        GeoPoint point = GeoUtils.parseGeoPoint(searchLookup.source().source().get("location"), true);
+                        Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                        GeoPoint point = GeoUtils.parseGeoPoint(source.get("location"), true);
                         emit(point.lat(), point.lon());
                     }
                 };

server/src/test/java/org/elasticsearch/search/runtime/LongScriptFieldDistanceFeatureQueryTests.java

@@ -22,7 +22,7 @@ import org.elasticsearch.script.AbstractLongFieldScript;
 import org.elasticsearch.script.DateFieldScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
@@ -70,7 +70,7 @@ public class LongScriptFieldDistanceFeatureQueryTests extends AbstractScriptFiel
             iw.addDocument(List.of(new StoredField("_source", new BytesRef("{\"timestamp\": [1595432181351]}"))));
             try (DirectoryReader reader = iw.getReader()) {
                 IndexSearcher searcher = newSearcher(reader);
-                SearchLookup searchLookup = new SearchLookup(null, null, new SourceLookup.ReaderSourceProvider());
+                SearchLookup searchLookup = new SearchLookup(null, null, SourceProvider.fromStoredFields());
                 Function<LeafReaderContext, AbstractLongFieldScript> leafFactory = ctx -> new DateFieldScript(
                     "test",
                     Map.of(),
@@ -80,8 +80,10 @@ public class LongScriptFieldDistanceFeatureQueryTests extends AbstractScriptFiel
                     ctx
                 ) {
                     @Override
+                    @SuppressWarnings("unchecked")
                     public void execute() {
-                        for (Object timestamp : (List<?>) searchLookup.source().source().get("timestamp")) {
+                        Map<String, Object> source = (Map<String, Object>) this.getParams().get("_source");
+                        for (Object timestamp : (List<?>) source.get("timestamp")) {
                             emit(((Number) timestamp).longValue());
                         }
                     }

test/framework/src/main/java/org/elasticsearch/index/mapper/FieldTypeTestCase.java

@@ -11,7 +11,6 @@ import org.elasticsearch.Version;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.search.lookup.SearchLookup;
 import org.elasticsearch.search.lookup.Source;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.xcontent.XContentType;
 
@@ -38,9 +37,7 @@ public abstract class FieldTypeTestCase extends ESTestCase {
         SearchExecutionContext searchExecutionContext = mock(SearchExecutionContext.class);
         when(searchExecutionContext.allowExpensiveQueries()).thenReturn(allowExpensiveQueries);
         when(searchExecutionContext.isSourceEnabled()).thenReturn(true);
-        SourceLookup sourceLookup = mock(SourceLookup.class);
         SearchLookup searchLookup = mock(SearchLookup.class);
-        when(searchLookup.source()).thenReturn(sourceLookup);
         when(searchExecutionContext.lookup()).thenReturn(searchLookup);
         when(searchExecutionContext.indexVersionCreated()).thenReturn(Version.CURRENT);
         return searchExecutionContext;

test/framework/src/main/java/org/elasticsearch/index/mapper/MapperTestCase.java

@@ -49,7 +49,8 @@ import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.lookup.LeafStoredFieldsLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xcontent.ToXContent;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.json.JsonXContent;
@@ -509,14 +510,14 @@ public abstract class MapperTestCase extends MapperServiceTestCase {
                 SearchLookup lookup = new SearchLookup(
                     mapperService::fieldType,
                     fieldDataLookup(mapperService),
-                    new SourceLookup.ReaderSourceProvider()
+                    SourceProvider.fromStoredFields()
                 );
                 ValueFetcher valueFetcher = new DocValueFetcher(format, lookup.getForField(ft, MappedFieldType.FielddataOperation.SEARCH));
                 IndexSearcher searcher = newSearcher(iw);
                 LeafReaderContext context = searcher.getIndexReader().leaves().get(0);
-                lookup.source().setSegmentAndDocument(context, 0);
+                Source source = lookup.getSource(context, 0);
                 valueFetcher.setNextReader(context);
-                result.set(valueFetcher.fetchValues(lookup.source(), 0, new ArrayList<>()));
+                result.set(valueFetcher.fetchValues(source, 0, new ArrayList<>()));
             }
         );
         return result.get();
@@ -530,7 +531,10 @@ public abstract class MapperTestCase extends MapperServiceTestCase {
             iw -> {
                 IndexSearcher searcher = newSearcher(iw);
                 MappedFieldType ft = mapperService.fieldType("field");
-                SearchLookup searchLookup = new SearchLookup(null, null, mapperService.mappingLookup().getSourceProvider());
+                SourceProvider sourceProvider = mapperService.mappingLookup().isSourceSynthetic()
+                    ? (ctx, doc) -> { throw new IllegalArgumentException("Can't load source in scripts in synthetic mode"); }
+                    : SourceProvider.fromStoredFields();
+                SearchLookup searchLookup = new SearchLookup(null, null, sourceProvider);
                 IndexFieldData<?> sfd = ft.fielddataBuilder(
                     new FieldDataContext("", () -> searchLookup, Set::of, MappedFieldType.FielddataOperation.SCRIPT)
                 ).build(null, null);
@@ -811,12 +815,11 @@ public abstract class MapperTestCase extends MapperServiceTestCase {
         ValueFetcher nativeFetcher = ft.valueFetcher(searchExecutionContext, format);
         ParsedDocument doc = mapperService.documentMapper().parse(source);
         withLuceneIndex(mapperService, iw -> iw.addDocuments(doc.docs()), ir -> {
-            SourceLookup sourceLookup = new SourceLookup(new SourceLookup.ReaderSourceProvider());
-            sourceLookup.setSegmentAndDocument(ir.leaves().get(0), 0);
+            Source s = SourceProvider.fromStoredFields().getSource(ir.leaves().get(0), 0);
             docValueFetcher.setNextReader(ir.leaves().get(0));
             nativeFetcher.setNextReader(ir.leaves().get(0));
-            List<Object> fromDocValues = docValueFetcher.fetchValues(sourceLookup, 0, new ArrayList<>());
-            List<Object> fromNative = nativeFetcher.fetchValues(sourceLookup, 0, new ArrayList<>());
+            List<Object> fromDocValues = docValueFetcher.fetchValues(s, 0, new ArrayList<>());
+            List<Object> fromNative = nativeFetcher.fetchValues(s, 0, new ArrayList<>());
             /*
              * The native fetcher uses byte, short, etc but doc values always
              * uses long or double. This difference is fine because on the outside
@@ -923,7 +926,7 @@ public abstract class MapperTestCase extends MapperServiceTestCase {
         SearchLookup lookup = new SearchLookup(
             f -> fieldType,
             (f, s, t) -> { throw new UnsupportedOperationException(); },
-            new SourceLookup.ReaderSourceProvider()
+            (ctx, docid) -> Source.fromBytes(doc.source())
         );
 
         withLuceneIndex(mapperService, iw -> iw.addDocument(doc.rootDoc()), ir -> {

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/cluster/routing/allocation/mapper/DataTierFieldTypeTests.java

@@ -20,7 +20,8 @@ import org.elasticsearch.index.mapper.MapperServiceTestCase;
 import org.elasticsearch.index.mapper.ValueFetcher;
 import org.elasticsearch.index.query.QueryShardException;
 import org.elasticsearch.index.query.SearchExecutionContext;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -88,14 +89,14 @@ public class DataTierFieldTypeTests extends MapperServiceTestCase {
 
     public void testFetchValue() throws IOException {
         MappedFieldType ft = DataTierFieldMapper.DataTierFieldType.INSTANCE;
-        SourceLookup lookup = new SourceLookup(new SourceLookup.NullSourceProvider());
+        Source source = Source.empty(XContentType.JSON);
 
         List<Object> ignoredValues = new ArrayList<>();
         ValueFetcher valueFetcher = ft.valueFetcher(createContext(), null);
-        assertEquals(singletonList("data_warm"), valueFetcher.fetchValues(lookup, -1, ignoredValues));
+        assertEquals(singletonList("data_warm"), valueFetcher.fetchValues(source, -1, ignoredValues));
 
         ValueFetcher emptyValueFetcher = ft.valueFetcher(createContextWithoutSetting(), null);
-        assertTrue(emptyValueFetcher.fetchValues(lookup, -1, ignoredValues).isEmpty());
+        assertTrue(emptyValueFetcher.fetchValues(source, -1, ignoredValues).isEmpty());
     }
 
     private SearchExecutionContext createContext() {

x-pack/plugin/mapper-aggregate-metric/src/test/java/org/elasticsearch/xpack/aggregatemetric/mapper/AggregateDoubleMetricFieldTypeTests.java

@@ -27,7 +27,6 @@ import org.elasticsearch.script.DocReader;
 import org.elasticsearch.script.ScoreScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.lookup.SearchLookup;
-import org.elasticsearch.search.lookup.SourceLookup;
 import org.elasticsearch.xpack.aggregatemetric.mapper.AggregateDoubleMetricFieldMapper.AggregateDoubleMetricFieldType;
 import org.elasticsearch.xpack.aggregatemetric.mapper.AggregateDoubleMetricFieldMapper.Metric;
 
@@ -127,7 +126,7 @@ public class AggregateDoubleMetricFieldTypeTests extends FieldTypeTestCase {
                     (mft, lookupSupplier, fdo) -> mft.fielddataBuilder(
                         new FieldDataContext("test", lookupSupplier, searchExecutionContext::sourcePath, fdo)
                     ).build(null, null),
-                    new SourceLookup.ReaderSourceProvider()
+                    (ctx, doc) -> null
                 );
                 when(searchExecutionContext.lookup()).thenReturn(lookup);
                 IndexSearcher searcher = newSearcher(reader);

x-pack/plugin/mapper-unsigned-long/src/main/java/org/elasticsearch/xpack/unsignedlong/SourceValueFetcherSortedUnsignedLongIndexFieldData.java

@@ -16,7 +16,8 @@ import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.script.field.DocValuesScriptFieldFactory;
 import org.elasticsearch.script.field.ToScriptFieldFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceProvider;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -40,10 +41,10 @@ public class SourceValueFetcherSortedUnsignedLongIndexFieldData extends SourceVa
             String fieldName,
             ValuesSourceType valuesSourceType,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup,
+            SourceProvider sourceProvider,
             ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory
         ) {
-            super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+            super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
         }
 
         @Override
@@ -52,7 +53,7 @@ public class SourceValueFetcherSortedUnsignedLongIndexFieldData extends SourceVa
                 fieldName,
                 valuesSourceType,
                 valueFetcher,
-                sourceLookup,
+                sourceProvider,
                 toScriptFieldFactory
             );
         }
@@ -62,15 +63,15 @@ public class SourceValueFetcherSortedUnsignedLongIndexFieldData extends SourceVa
         String fieldName,
         ValuesSourceType valuesSourceType,
         ValueFetcher valueFetcher,
-        SourceLookup sourceLookup,
+        SourceProvider sourceProvider,
         ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory
     ) {
-        super(fieldName, valuesSourceType, valueFetcher, sourceLookup, toScriptFieldFactory);
+        super(fieldName, valuesSourceType, valueFetcher, sourceProvider, toScriptFieldFactory);
     }
 
     @Override
     public SourceValueFetcherLeafFieldData<SortedNumericDocValues> loadDirect(LeafReaderContext context) {
-        return new SourceValueFetcherSortedUnsignedLongLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceLookup);
+        return new SourceValueFetcherSortedUnsignedLongLeafFieldData(toScriptFieldFactory, context, valueFetcher, sourceProvider);
     }
 
     private static class SourceValueFetcherSortedUnsignedLongLeafFieldData extends SourceValueFetcherLeafFieldData<SortedNumericDocValues> {
@@ -79,15 +80,15 @@ public class SourceValueFetcherSortedUnsignedLongIndexFieldData extends SourceVa
             ToScriptFieldFactory<SortedNumericDocValues> toScriptFieldFactory,
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
-            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceLookup);
+            super(toScriptFieldFactory, leafReaderContext, valueFetcher, sourceProvider);
         }
 
         @Override
         public DocValuesScriptFieldFactory getScriptFieldFactory(String name) {
             return toScriptFieldFactory.getScriptFieldFactory(
-                new SourceValueFetcherSortedUnsignedLongDocValues(leafReaderContext, valueFetcher, sourceLookup),
+                new SourceValueFetcherSortedUnsignedLongDocValues(leafReaderContext, valueFetcher, sourceProvider),
                 name
             );
         }
@@ -98,7 +99,7 @@ public class SourceValueFetcherSortedUnsignedLongIndexFieldData extends SourceVa
         private final LeafReaderContext leafReaderContext;
 
         private final ValueFetcher valueFetcher;
-        private final SourceLookup sourceLookup;
+        private final SourceProvider sourceProvider;
 
         private List<Long> values;
         private Iterator<Long> iterator;
@@ -106,21 +107,20 @@ public class SourceValueFetcherSortedUnsignedLongIndexFieldData extends SourceVa
         private SourceValueFetcherSortedUnsignedLongDocValues(
             LeafReaderContext leafReaderContext,
             ValueFetcher valueFetcher,
-            SourceLookup sourceLookup
+            SourceProvider sourceProvider
         ) {
             this.leafReaderContext = leafReaderContext;
             this.valueFetcher = valueFetcher;
-            this.sourceLookup = sourceLookup;
+            this.sourceProvider = sourceProvider;
 
             values = new ArrayList<>();
         }
 
         @Override
         public boolean advanceExact(int doc) throws IOException {
-            sourceLookup.setSegmentAndDocument(leafReaderContext, doc);
             values.clear();
-
-            for (Object value : valueFetcher.fetchValues(sourceLookup, doc, Collections.emptyList())) {
+            Source source = sourceProvider.getSource(leafReaderContext, doc);
+            for (Object value : valueFetcher.fetchValues(source, doc, Collections.emptyList())) {
                 assert value instanceof Number;
                 values.add(((Number) value).longValue() ^ MASK_2_63);
             }

x-pack/plugin/mapper-unsigned-long/src/main/java/org/elasticsearch/xpack/unsignedlong/UnsignedLongFieldMapper.java

@@ -322,7 +322,7 @@ public class UnsignedLongFieldMapper extends FieldMapper {
                     name(),
                     valuesSourceType,
                     sourceValueFetcher(sourcePaths),
-                    searchLookup.source(),
+                    searchLookup,
                     UnsignedLongDocValuesField::new
                 );
             }

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/CategorizeTextAggregator.java

@@ -10,8 +10,10 @@ package org.elasticsearch.xpack.ml.aggs.categorization;
 import org.apache.lucene.analysis.Analyzer;
 import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.util.BytesRefHash;
 import org.elasticsearch.common.util.ObjectArray;
+import org.elasticsearch.common.xcontent.support.XContentMapValues;
 import org.elasticsearch.core.Releasables;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.search.aggregations.AggregationExecutionContext;
@@ -25,7 +27,9 @@ import org.elasticsearch.search.aggregations.bucket.DeferableBucketAggregator;
 import org.elasticsearch.search.aggregations.bucket.terms.LongKeyedBucketOrds;
 import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregator;
 import org.elasticsearch.search.aggregations.support.AggregationContext;
-import org.elasticsearch.search.lookup.SourceLookup;
+import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceFilter;
+import org.elasticsearch.search.lookup.SourceProvider;
 import org.elasticsearch.xpack.core.ml.job.config.CategorizationAnalyzerConfig;
 import org.elasticsearch.xpack.ml.aggs.categorization.InternalCategorizationAggregation.Bucket;
 import org.elasticsearch.xpack.ml.job.categorization.CategorizationAnalyzer;
@@ -40,7 +44,8 @@ import java.util.Optional;
 public class CategorizeTextAggregator extends DeferableBucketAggregator {
 
     private final TermsAggregator.BucketCountThresholds bucketCountThresholds;
-    private final SourceLookup sourceLookup;
+    private final SourceProvider sourceProvider;
+    private final SourceFilter sourceFilter;
     private final MappedFieldType fieldType;
     private final CategorizationAnalyzer analyzer;
     private final String sourceFieldName;
@@ -63,8 +68,9 @@ public class CategorizeTextAggregator extends DeferableBucketAggregator {
         Map<String, Object> metadata
     ) throws IOException {
         super(name, factories, context, parent, metadata);
-        this.sourceLookup = context.lookup().source();
+        this.sourceProvider = context.lookup();
         this.sourceFieldName = sourceFieldName;
+        this.sourceFilter = new SourceFilter(new String[] { sourceFieldName }, Strings.EMPTY_ARRAY);
         this.fieldType = fieldType;
         CategorizationAnalyzerConfig analyzerConfig = Optional.ofNullable(categorizationAnalyzerConfig)
             .orElse(CategorizationAnalyzerConfig.buildStandardCategorizationAnalyzer(List.of()));
@@ -156,8 +162,8 @@ public class CategorizeTextAggregator extends DeferableBucketAggregator {
             }
 
             private void collectFromSource(int doc, long owningBucketOrd, TokenListCategorizer categorizer) throws IOException {
-                sourceLookup.setSegmentAndDocument(aggCtx.getLeafReaderContext(), doc);
-                Iterator<String> itr = sourceLookup.extractRawValuesWithoutCaching(sourceFieldName).stream().map(obj -> {
+                Source source = sourceProvider.getSource(aggCtx.getLeafReaderContext(), doc).filter(sourceFilter);
+                Iterator<String> itr = XContentMapValues.extractRawValues(sourceFieldName, source.source()).stream().map(obj -> {
                     if (obj instanceof BytesRef) {
                         return fieldType.valueForDisplay(obj).toString();
                     }