Retrieve value from DocValues in a flat_object filed (opensearch-proj…

…ect#16802)

optimize innerhit phase

CHANGELOG.md

@@ -24,6 +24,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Added a precaution to handle extreme date values during sorting to prevent `arithmetic_exception: long overflow` ([#16812](https://github.com/opensearch-project/OpenSearch/pull/16812)).
 - Add search replica stats to segment replication stats API ([#16678](https://github.com/opensearch-project/OpenSearch/pull/16678))
 - Introduce a setting to disable download of full cluster state from remote on term mismatch([#16798](https://github.com/opensearch-project/OpenSearch/pull/16798/))
+- Added ability to retrieve value from DocValues in a flat_object filed([#16802](https://github.com/opensearch-project/OpenSearch/pull/16802))
 
 ### Dependencies
 - Bump `com.google.cloud:google-cloud-core-http` from 2.23.0 to 2.47.0 ([#16504](https://github.com/opensearch-project/OpenSearch/pull/16504))

rest-api-spec/src/main/resources/rest-api-spec/test/index/92_flat_object_support_doc_values.yml

@@ -1,8 +1,9 @@
 ---
 # The test setup includes:
-# - Create flat_object mapping for flat_object_doc_values_test index
-# - Index 9 example documents
-# - Search tests about doc_values and index
+# - 1.Create flat_object mapping for flat_object_doc_values_test index
+# - 2.Index 9 example documents
+# - 3.Search tests about doc_values and index
+# - 4.Fetch doc_value from flat_object field
 
 setup:
   - skip:
@@ -786,3 +787,48 @@ teardown:
 
   - length: { hits.hits: 1 }
   - match: { hits.hits.0._source.order: "order8" }
+
+  # Stored Fields with exact dot path.
+  - do:
+      search:
+        body: {
+          _source: false,
+          query: {
+            bool: {
+              must: [
+                {
+                  term: {
+                    order: "order0"
+                  }
+                }
+              ]
+            }
+          },
+          stored_fields: "_none_",
+          docvalue_fields: [ "issue.labels.name","order" ]
+        }
+
+  - length: { hits.hits: 1 }
+  - match: { hits.hits.0.fields: { "order" : [ "order0" ], "issue.labels.name": [ "abc0" ] } }
+
+  - do:
+      search:
+        body: {
+          _source: false,
+          query: {
+            bool: {
+              must: [
+                {
+                  term: {
+                    order: "order0"
+                  }
+                }
+              ]
+            }
+          },
+          stored_fields: "_none_",
+          docvalue_fields: [ "issue.labels.name" ]
+        }
+
+  - length: { hits.hits: 1 }
+  - match: { hits.hits.0.fields: { "issue.labels.name": [ "abc0" ] } }

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

@@ -1023,7 +1023,7 @@ public void testDocValueFields() throws Exception {
             .startObject("ip_field")
             .field("type", "ip")
             .endObject()
-            .startObject("flat_object_field")
+            .startObject("flat_object_field1")
             .field("type", "flat_object")
             .endObject()
             .endObject()
@@ -1050,9 +1050,11 @@ public void testDocValueFields() throws Exception {
                     .field("boolean_field", true)
                     .field("binary_field", new byte[] { 42, 100 })
                     .field("ip_field", "::1")
-                    .field("flat_object_field")
+                    .field("flat_object_field1")
                     .startObject()
+                    .field("fooa", "bara")
                     .field("foo", "bar")
+                    .field("foob", "barb")
                     .endObject()
                     .endObject()
             )
@@ -1075,7 +1077,7 @@ public void testDocValueFields() throws Exception {
             .addDocValueField("boolean_field")
             .addDocValueField("binary_field")
             .addDocValueField("ip_field")
-            .addDocValueField("flat_object_field");
+            .addDocValueField("flat_object_field1.foo");
         SearchResponse searchResponse = builder.get();
 
         assertThat(searchResponse.getHits().getTotalHits().value, equalTo(1L));
@@ -1097,7 +1099,7 @@ public void testDocValueFields() throws Exception {
                     "keyword_field",
                     "binary_field",
                     "ip_field",
-                    "flat_object_field"
+                    "flat_object_field1.foo"
                 )
             )
         );
@@ -1116,7 +1118,7 @@ public void testDocValueFields() throws Exception {
         assertThat(searchResponse.getHits().getAt(0).getFields().get("keyword_field").getValue(), equalTo("foo"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("ip_field").getValue(), equalTo("::1"));
-        assertThat(searchResponse.getHits().getAt(0).getFields().get("flat_object_field").getValue(), equalTo("flat_object_field.foo"));
+        assertThat(searchResponse.getHits().getAt(0).getFields().get("flat_object_field1.foo").getValue(), equalTo("bar"));
 
         builder = client().prepareSearch().setQuery(matchAllQuery()).addDocValueField("*field");
         searchResponse = builder.get();
@@ -1139,8 +1141,7 @@ public void testDocValueFields() throws Exception {
                     "text_field",
                     "keyword_field",
                     "binary_field",
-                    "ip_field",
-                    "flat_object_field"
+                    "ip_field"
                 )
             )
         );
@@ -1160,7 +1161,6 @@ public void testDocValueFields() throws Exception {
         assertThat(searchResponse.getHits().getAt(0).getFields().get("keyword_field").getValue(), equalTo("foo"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("ip_field").getValue(), equalTo("::1"));
-        assertThat(searchResponse.getHits().getAt(0).getFields().get("flat_object_field").getValue(), equalTo("flat_object_field.foo"));
 
         builder = client().prepareSearch()
             .setQuery(matchAllQuery())
@@ -1176,7 +1176,7 @@ public void testDocValueFields() throws Exception {
             .addDocValueField("boolean_field", "use_field_mapping")
             .addDocValueField("binary_field", "use_field_mapping")
             .addDocValueField("ip_field", "use_field_mapping")
-            .addDocValueField("flat_object_field", "use_field_mapping");
+            .addDocValueField("flat_object_field1.foo", null);
         ;
         searchResponse = builder.get();
 
@@ -1199,7 +1199,7 @@ public void testDocValueFields() throws Exception {
                     "keyword_field",
                     "binary_field",
                     "ip_field",
-                    "flat_object_field"
+                    "flat_object_field1.foo"
                 )
             )
         );
@@ -1219,7 +1219,7 @@ public void testDocValueFields() throws Exception {
         assertThat(searchResponse.getHits().getAt(0).getFields().get("keyword_field").getValue(), equalTo("foo"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("binary_field").getValue(), equalTo("KmQ"));
         assertThat(searchResponse.getHits().getAt(0).getFields().get("ip_field").getValue(), equalTo("::1"));
-        assertThat(searchResponse.getHits().getAt(0).getFields().get("flat_object_field").getValue(), equalTo("flat_object_field.foo"));
+        assertThat(searchResponse.getHits().getAt(0).getFields().get("flat_object_field1.foo").getValue(), equalTo("bar"));
 
         builder = client().prepareSearch()
             .setQuery(matchAllQuery())

server/src/main/java/org/opensearch/index/mapper/DocValueFetcher.java

@@ -43,6 +43,7 @@
 import java.util.List;
 
 import static java.util.Collections.emptyList;
+import static org.opensearch.index.mapper.FlatObjectFieldMapper.DOC_VALUE_NO_MATCH;
 
 /**
  * Value fetcher that loads from doc values.
@@ -70,7 +71,10 @@ public List<Object> fetchValues(SourceLookup lookup) throws IOException {
         }
         List<Object> result = new ArrayList<Object>(leaf.docValueCount());
         for (int i = 0, count = leaf.docValueCount(); i < count; ++i) {
-            result.add(leaf.nextValue());
+            Object value = leaf.nextValue();
+            if (value != DOC_VALUE_NO_MATCH) {
+                result.add(value);
+            }
         }
         return result;
     }

server/src/main/java/org/opensearch/index/mapper/DocumentMapper.java

@@ -38,6 +38,7 @@
 import org.apache.lucene.search.ScoreMode;
 import org.apache.lucene.search.Scorer;
 import org.apache.lucene.search.Weight;
+import org.apache.lucene.util.BitSet;
 import org.apache.lucene.util.BytesRef;
 import org.opensearch.OpenSearchGenerationException;
 import org.opensearch.common.annotation.PublicApi;
@@ -53,6 +54,8 @@
 import org.opensearch.index.analysis.IndexAnalyzers;
 import org.opensearch.index.mapper.MapperService.MergeReason;
 import org.opensearch.index.mapper.MetadataFieldMapper.TypeParser;
+import org.opensearch.index.query.NestedQueryBuilder;
+import org.opensearch.search.fetch.subphase.InnerHitsContext;
 import org.opensearch.search.internal.SearchContext;
 
 import java.io.IOException;
@@ -270,25 +273,15 @@ public ParsedDocument createNoopTombstoneDoc(String index, String reason) throws
      * Returns the best nested {@link ObjectMapper} instances that is in the scope of the specified nested docId.
      */
     public ObjectMapper findNestedObjectMapper(int nestedDocId, SearchContext sc, LeafReaderContext context) throws IOException {
+        if (sc instanceof NestedQueryBuilder.NestedInnerHitSubContext) {
+            ObjectMapper objectMapper = ((NestedQueryBuilder.NestedInnerHitSubContext) sc).getChildObjectMapper();
+            assert objectMappers().containsKey(objectMapper.fullPath());
+            assert containSubDocIdWithObjectMapper(nestedDocId, objectMapper, sc, context);
+            return objectMapper;
+        }
         ObjectMapper nestedObjectMapper = null;
         for (ObjectMapper objectMapper : objectMappers().values()) {
-            if (!objectMapper.nested().isNested()) {
-                continue;
-            }
-
-            Query filter = objectMapper.nestedTypeFilter();
-            if (filter == null) {
-                continue;
-            }
-            // We can pass down 'null' as acceptedDocs, because nestedDocId is a doc to be fetched and
-            // therefore is guaranteed to be a live doc.
-            final Weight nestedWeight = filter.createWeight(sc.searcher(), ScoreMode.COMPLETE_NO_SCORES, 1f);
-            Scorer scorer = nestedWeight.scorer(context);
-            if (scorer == null) {
-                continue;
-            }
-
-            if (scorer.iterator().advance(nestedDocId) == nestedDocId) {
+            if(containSubDocIdWithObjectMapper(nestedDocId, objectMapper, sc, context)) {
                 if (nestedObjectMapper == null) {
                     nestedObjectMapper = objectMapper;
                 } else {
@@ -301,6 +294,26 @@ public ObjectMapper findNestedObjectMapper(int nestedDocId, SearchContext sc, Le
         return nestedObjectMapper;
     }
 
+    private boolean containSubDocIdWithObjectMapper(int nestedDocId, ObjectMapper objectMapper,
+                                                    SearchContext sc, LeafReaderContext context) throws IOException {
+        if (!objectMapper.nested().isNested()) {
+            return false;
+        }
+        Query filter = objectMapper.nestedTypeFilter();
+        if (filter == null) {
+            return false;
+        }
+        // We can pass down 'null' as acceptedDocs, because nestedDocId is a doc to be fetched and
+        // therefore is guaranteed to be a live doc.
+        BitSet nesteDocIds = sc.bitsetFilterCache().getBitSetProducer(filter).getBitSet(context);
+        boolean result;
+        if (nesteDocIds != null && nesteDocIds.get(nestedDocId)) {
+           return true;
+        } else {
+            return false;
+        }
+    }
+
     public DocumentMapper merge(Mapping mapping, MergeReason reason) {
         Mapping merged = this.mapping.merge(mapping, reason);
         return new DocumentMapper(mapperService, merged);

server/src/main/java/org/opensearch/index/mapper/FlatObjectFieldMapper.java

@@ -28,6 +28,7 @@
 import org.opensearch.common.unit.Fuzziness;
 import org.opensearch.common.xcontent.JsonToStringXContentParser;
 import org.opensearch.core.common.ParsingException;
+import org.opensearch.core.common.io.stream.StreamOutput;
 import org.opensearch.core.xcontent.DeprecationHandler;
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.core.xcontent.XContentParser;
@@ -36,11 +37,13 @@
 import org.opensearch.index.fielddata.plain.SortedSetOrdinalsIndexFieldData;
 import org.opensearch.index.mapper.KeywordFieldMapper.KeywordFieldType;
 import org.opensearch.index.query.QueryShardContext;
+import org.opensearch.search.DocValueFormat;
 import org.opensearch.search.aggregations.support.CoreValuesSourceType;
 import org.opensearch.search.lookup.SearchLookup;
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
@@ -63,6 +66,7 @@
 public final class FlatObjectFieldMapper extends DynamicKeyFieldMapper {
 
     public static final String CONTENT_TYPE = "flat_object";
+    public static final Object DOC_VALUE_NO_MATCH = new Object();
 
     /**
      * In flat_object field mapper, field type is similar to keyword field type
@@ -272,7 +276,7 @@ NamedAnalyzer normalizer() {
         @Override
         public IndexFieldData.Builder fielddataBuilder(String fullyQualifiedIndexName, Supplier<SearchLookup> searchLookup) {
             failIfNoDocValues();
-            return new SortedSetOrdinalsIndexFieldData.Builder(name(), CoreValuesSourceType.BYTES);
+            return new SortedSetOrdinalsIndexFieldData.Builder(valueFieldType().name(), CoreValuesSourceType.BYTES);
         }
 
         @Override
@@ -304,6 +308,30 @@ protected String parseSourceValue(Object value) {
             };
         }
 
+        @Override
+        public DocValueFormat docValueFormat(@Nullable String format, ZoneId timeZone) {
+            if (format != null) {
+                throw new IllegalArgumentException("Field [" + name() + "] of type [" + typeName() + "] does not support custom formats");
+            }
+            if (timeZone != null) {
+                throw new IllegalArgumentException(
+                    "Field [" + name() + "] of type [" + typeName() + "] does not support custom time zones"
+                );
+            }
+            if (mappedFieldTypeName != null) {
+                return new FlatObjectDocValueFormat(mappedFieldTypeName + DOT_SYMBOL + name() + EQUAL_SYMBOL);
+            } else {
+                throw new IllegalArgumentException(
+                    "Field [" + name() + "] of type [" + typeName() + "] does not support doc_value in root field"
+                );
+            }
+        }
+
+        @Override
+        public boolean isAggregatable() {
+            return false;
+        }
+
         @Override
         public Object valueForDisplay(Object value) {
             if (value == null) {
@@ -530,6 +558,39 @@ public Query wildcardQuery(
             return valueFieldType().wildcardQuery(rewriteValue(value), method, caseInsensitve, context);
         }
 
+        /**
+         * A doc_value formatter for flat_object field.
+         */
+        public class FlatObjectDocValueFormat implements DocValueFormat {
+            private static final String NAME = "flat_object";
+            private final String prefix;
+
+            public FlatObjectDocValueFormat(String prefix) {
+                this.prefix = prefix;
+            }
+
+            @Override
+            public String getWriteableName() {
+                return NAME;
+            }
+
+            @Override
+            public void writeTo(StreamOutput out) {}
+
+            @Override
+            public Object format(BytesRef value) {
+                String parsedValue = inputToString(value);
+                if (parsedValue.startsWith(prefix) == false) {
+                    return DOC_VALUE_NO_MATCH;
+                }
+                return parsedValue.substring(prefix.length());
+            }
+
+            @Override
+            public BytesRef parseBytesRef(String value) {
+                return new BytesRef((String) valueFieldType.rewriteForDocValue(rewriteValue(value)));
+            }
+        }
     }
 
     private final ValueFieldMapper valueFieldMapper;

server/src/main/java/org/opensearch/index/query/NestedQueryBuilder.java

@@ -438,7 +438,7 @@ protected void doBuild(SearchContext parentSearchContext, InnerHitsContext inner
      *
      * @opensearch.internal
      */
-    static final class NestedInnerHitSubContext extends InnerHitsContext.InnerHitSubContext {
+    public static final class NestedInnerHitSubContext extends InnerHitsContext.InnerHitSubContext {
 
         private final ObjectMapper parentObjectMapper;
         private final ObjectMapper childObjectMapper;
@@ -507,6 +507,10 @@ public TopDocsAndMaxScore topDocs(SearchHit hit) throws IOException {
                 return new TopDocsAndMaxScore(td, maxScore);
             }
         }
+
+        public ObjectMapper getChildObjectMapper() {
+            return childObjectMapper;
+        }
     }
 
     @Override