Add Optional Source Filtering to Source Loaders (#113827)

This change introduces optional source filtering directly within source loaders (both synthetic and stored).
The main benefit is seen in synthetic source loaders, as synthetic fields are stored independently.
By filtering while loading the synthetic source, generating the source becomes linear in the number of fields that match the filter.

This update also modifies the get document API to apply source filters earlier—directly through the source loader.
The search API, however, is not affected in this change, since the loaded source is still used by other features (e.g., highlighting, fields, nested hits),
and source filtering is always applied as the final step.
A follow-up will be required to ensure careful handling of all search-related scenarios.

Author: jimczi

benchmarks/src/main/java/org/elasticsearch/benchmark/search/fetch/subphase/FetchSourcePhaseBenchmark.java

@@ -63,7 +63,7 @@ public void setup() throws IOException {
         );
         includesSet = Set.of(fetchContext.includes());
         excludesSet = Set.of(fetchContext.excludes());
-        parserConfig = XContentParserConfiguration.EMPTY.withFiltering(includesSet, excludesSet, false);
+        parserConfig = XContentParserConfiguration.EMPTY.withFiltering(null, includesSet, excludesSet, false);
     }
 
     private BytesReference read300BytesExample() throws IOException {

benchmarks/src/main/java/org/elasticsearch/benchmark/xcontent/FilterContentBenchmark.java

@@ -170,7 +170,7 @@ private XContentParserConfiguration buildParseConfig(boolean matchDotsInFieldNam
             includes = null;
             excludes = filters;
         }
-        return XContentParserConfiguration.EMPTY.withFiltering(includes, excludes, matchDotsInFieldNames);
+        return XContentParserConfiguration.EMPTY.withFiltering(null, includes, excludes, matchDotsInFieldNames);
     }
 
     private BytesReference filter(XContentParserConfiguration contentParserConfiguration) throws IOException {

docs/changelog/113827.yaml

@@ -0,0 +1,5 @@
+pr: 113827
+summary: Add Optional Source Filtering to Source Loaders
+area: Mapping
+type: enhancement
+issues: []

libs/x-content/impl/src/main/java/org/elasticsearch/xcontent/provider/XContentParserConfigurationImpl.java

@@ -19,6 +19,8 @@
 import org.elasticsearch.xcontent.provider.filtering.FilterPathBasedFilter;
 import org.elasticsearch.xcontent.support.filtering.FilterPath;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Set;
 
 public class XContentParserConfigurationImpl implements XContentParserConfiguration {
@@ -106,12 +108,41 @@ public XContentParserConfiguration withFiltering(
         Set<String> excludeStrings,
         boolean filtersMatchFieldNamesWithDots
     ) {
+        return withFiltering(null, includeStrings, excludeStrings, filtersMatchFieldNamesWithDots);
+    }
+
+    public XContentParserConfiguration withFiltering(
+        String prefixPath,
+        Set<String> includeStrings,
+        Set<String> excludeStrings,
+        boolean filtersMatchFieldNamesWithDots
+    ) {
+        FilterPath[] includePaths = FilterPath.compile(includeStrings);
+        FilterPath[] excludePaths = FilterPath.compile(excludeStrings);
+
+        if (prefixPath != null) {
+            if (includePaths != null) {
+                List<FilterPath> includeFilters = new ArrayList<>();
+                for (var incl : includePaths) {
+                    incl.matches(prefixPath, includeFilters, true);
+                }
+                includePaths = includeFilters.isEmpty() ? null : includeFilters.toArray(FilterPath[]::new);
+            }
+
+            if (excludePaths != null) {
+                List<FilterPath> excludeFilters = new ArrayList<>();
+                for (var excl : excludePaths) {
+                    excl.matches(prefixPath, excludeFilters, true);
+                }
+                excludePaths = excludeFilters.isEmpty() ? null : excludeFilters.toArray(FilterPath[]::new);
+            }
+        }
         return new XContentParserConfigurationImpl(
             registry,
             deprecationHandler,
             restApiVersion,
-            FilterPath.compile(includeStrings),
-            FilterPath.compile(excludeStrings),
+            includePaths,
+            excludePaths,
             filtersMatchFieldNamesWithDots
         );
     }

libs/x-content/src/main/java/org/elasticsearch/xcontent/XContentParserConfiguration.java

@@ -49,10 +49,27 @@ public interface XContentParserConfiguration {
 
     RestApiVersion restApiVersion();
 
+    // TODO: Remove when serverless uses the new API
+    XContentParserConfiguration withFiltering(
+        Set<String> includeStrings,
+        Set<String> excludeStrings,
+        boolean filtersMatchFieldNamesWithDots
+    );
+
     /**
      * Replace the configured filtering.
+     *
+     * @param prefixPath                    The path to be prepended to each sub-path before applying the include/exclude rules.
+     *                                      Specify {@code null} if parsing starts from the root.
+     * @param includeStrings                A set of strings representing paths to include during filtering.
+     *                                      If specified, only these paths will be included in parsing.
+     * @param excludeStrings                A set of strings representing paths to exclude during filtering.
+     *                                      If specified, these paths will be excluded from parsing.
+     * @param filtersMatchFieldNamesWithDots Indicates whether filters should match field names containing dots ('.')
+     *                                      as part of the field name.
      */
     XContentParserConfiguration withFiltering(
+        String prefixPath,
         Set<String> includeStrings,
         Set<String> excludeStrings,
         boolean filtersMatchFieldNamesWithDots

libs/x-content/src/test/java/org/elasticsearch/xcontent/support/filtering/AbstractXContentFilteringTestCase.java

@@ -22,6 +22,7 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.Set;
 import java.util.stream.IntStream;
 
@@ -332,6 +333,24 @@ protected final void testFilter(Builder expected, Builder sample, Collection<Str
     private void testFilter(Builder expected, Builder sample, Set<String> includes, Set<String> excludes, boolean matchFieldNamesWithDots)
         throws IOException {
         assertFilterResult(expected.apply(createBuilder()), filter(sample, includes, excludes, matchFieldNamesWithDots));
+
+        String rootPrefix = "root.path.random";
+        if (includes != null) {
+            Set<String> rootIncludes = new HashSet<>();
+            for (var incl : includes) {
+                rootIncludes.add(rootPrefix + (randomBoolean() ? "." : "*.") + incl);
+            }
+            includes = rootIncludes;
+        }
+
+        if (excludes != null) {
+            Set<String> rootExcludes = new HashSet<>();
+            for (var excl : excludes) {
+                rootExcludes.add(rootPrefix + (randomBoolean() ? "." : "*.") + excl);
+            }
+            excludes = rootExcludes;
+        }
+        assertFilterResult(expected.apply(createBuilder()), filterSub(sample, rootPrefix, includes, excludes, matchFieldNamesWithDots));
     }
 
     public void testArrayWithEmptyObjectInInclude() throws IOException {
@@ -413,21 +432,36 @@ private XContentBuilder filter(Builder sample, Set<String> includes, Set<String>
             && matchFieldNamesWithDots == false) {
             return filterOnBuilder(sample, includes, excludes);
         }
-        return filterOnParser(sample, includes, excludes, matchFieldNamesWithDots);
+        return filterOnParser(sample, null, includes, excludes, matchFieldNamesWithDots);
+    }
+
+    private XContentBuilder filterSub(
+        Builder sample,
+        String root,
+        Set<String> includes,
+        Set<String> excludes,
+        boolean matchFieldNamesWithDots
+    ) throws IOException {
+        return filterOnParser(sample, root, includes, excludes, matchFieldNamesWithDots);
     }
 
     private XContentBuilder filterOnBuilder(Builder sample, Set<String> includes, Set<String> excludes) throws IOException {
         return sample.apply(XContentBuilder.builder(getXContentType(), includes, excludes));
     }
 
-    private XContentBuilder filterOnParser(Builder sample, Set<String> includes, Set<String> excludes, boolean matchFieldNamesWithDots)
-        throws IOException {
+    private XContentBuilder filterOnParser(
+        Builder sample,
+        String rootPath,
+        Set<String> includes,
+        Set<String> excludes,
+        boolean matchFieldNamesWithDots
+    ) throws IOException {
         try (XContentBuilder builtSample = sample.apply(createBuilder())) {
             BytesReference sampleBytes = BytesReference.bytes(builtSample);
             try (
                 XContentParser parser = getXContentType().xContent()
                     .createParser(
-                        XContentParserConfiguration.EMPTY.withFiltering(includes, excludes, matchFieldNamesWithDots),
+                        XContentParserConfiguration.EMPTY.withFiltering(rootPath, includes, excludes, matchFieldNamesWithDots),
                         sampleBytes.streamInput()
                     )
             ) {

server/src/main/java/org/elasticsearch/action/update/UpdateHelper.java

@@ -35,6 +35,7 @@
 import org.elasticsearch.script.UpdateScript;
 import org.elasticsearch.script.UpsertCtxMap;
 import org.elasticsearch.search.lookup.Source;
+import org.elasticsearch.search.lookup.SourceFilter;
 import org.elasticsearch.xcontent.XContentType;
 
 import java.io.IOException;
@@ -340,8 +341,9 @@ public static GetResult extractGetResult(
             return null;
         }
         BytesReference sourceFilteredAsBytes = sourceAsBytes;
-        if (request.fetchSource().hasFilter()) {
-            sourceFilteredAsBytes = Source.fromMap(source, sourceContentType).filter(request.fetchSource().filter()).internalSourceRef();
+        SourceFilter sourceFilter = request.fetchSource().filter();
+        if (sourceFilter != null) {
+            sourceFilteredAsBytes = Source.fromMap(source, sourceContentType).filter(sourceFilter).internalSourceRef();
         }
 
         // TODO when using delete/none, we can still return the source as bytes by generating it (using the sourceContentType)

server/src/main/java/org/elasticsearch/cluster/metadata/DataStream.java

@@ -1361,6 +1361,7 @@ public DataStream getParentDataStream() {
     }
 
     public static final XContentParserConfiguration TS_EXTRACT_CONFIG = XContentParserConfiguration.EMPTY.withFiltering(
+        null,
         Set.of(TIMESTAMP_FIELD_NAME),
         null,
         false

server/src/main/java/org/elasticsearch/cluster/routing/IndexRouting.java

@@ -283,7 +283,7 @@ public static class ExtractFromSource extends IndexRouting {
             trackTimeSeriesRoutingHash = metadata.getCreationVersion().onOrAfter(IndexVersions.TIME_SERIES_ROUTING_HASH_IN_ID);
             List<String> routingPaths = metadata.getRoutingPaths();
             isRoutingPath = Regex.simpleMatcher(routingPaths.toArray(String[]::new));
-            this.parserConfig = XContentParserConfiguration.EMPTY.withFiltering(Set.copyOf(routingPaths), null, true);
+            this.parserConfig = XContentParserConfiguration.EMPTY.withFiltering(null, Set.copyOf(routingPaths), null, true);
         }
 
         public boolean matchesField(String fieldName) {

server/src/main/java/org/elasticsearch/common/xcontent/XContentHelper.java

@@ -192,7 +192,7 @@ public static Tuple<XContentType, Map<String, Object>> convertToMap(
     ) throws ElasticsearchParseException {
         XContentParserConfiguration config = XContentParserConfiguration.EMPTY;
         if (include != null || exclude != null) {
-            config = config.withFiltering(include, exclude, false);
+            config = config.withFiltering(null, include, exclude, false);
         }
         return parseToType(ordered ? XContentParser::mapOrdered : XContentParser::map, bytes, xContentType, config);
     }
@@ -267,7 +267,10 @@ public static Map<String, Object> convertToMap(
         @Nullable Set<String> exclude
     ) throws ElasticsearchParseException {
         try (
-            XContentParser parser = xContent.createParser(XContentParserConfiguration.EMPTY.withFiltering(include, exclude, false), input)
+            XContentParser parser = xContent.createParser(
+                XContentParserConfiguration.EMPTY.withFiltering(null, include, exclude, false),
+                input
+            )
         ) {
             return ordered ? parser.mapOrdered() : parser.map();
         } catch (IOException e) {
@@ -302,7 +305,7 @@ public static Map<String, Object> convertToMap(
     ) throws ElasticsearchParseException {
         try (
             XContentParser parser = xContent.createParser(
-                XContentParserConfiguration.EMPTY.withFiltering(include, exclude, false),
+                XContentParserConfiguration.EMPTY.withFiltering(null, include, exclude, false),
                 bytes,
                 offset,
                 length