Bug #42997

modules/parent-join/src/main/java/org/elasticsearch/join/aggregations/ChildrenAggregationBuilder.java

@@ -112,16 +112,21 @@ protected ValuesSourceConfig<WithOrdinals> resolveConfig(QueryShardContext query
 
     private void joinFieldResolveConfig(QueryShardContext queryShardContext, ValuesSourceConfig<WithOrdinals> config) {
         ParentJoinFieldMapper parentJoinFieldMapper = ParentJoinFieldMapper.getMapper(queryShardContext.getMapperService());
+        if (parentJoinFieldMapper != null) {
+            config.unmapped(true);
+            return;
+        }
         ParentIdFieldMapper parentIdFieldMapper = parentJoinFieldMapper.getParentIdFieldMapper(childType, false);
         if (parentIdFieldMapper != null) {
-            parentFilter = parentIdFieldMapper.getParentFilter();
-            childFilter = parentIdFieldMapper.getChildFilter(childType);
-            MappedFieldType fieldType = parentIdFieldMapper.fieldType();
-            final SortedSetDVOrdinalsIndexFieldData fieldData = queryShardContext.getForField(fieldType);
-            config.fieldContext(new FieldContext(fieldType.name(), fieldData, fieldType));
-        } else {
             config.unmapped(true);
+            return;
         }
+        parentFilter = parentIdFieldMapper.getParentFilter();
+        childFilter = parentIdFieldMapper.getChildFilter(childType);
+        MappedFieldType fieldType = parentIdFieldMapper.fieldType();
+        final SortedSetDVOrdinalsIndexFieldData fieldData = queryShardContext.getForField(fieldType);
+        config.fieldContext(new FieldContext(fieldType.name(), fieldData, fieldType));
+
     }
 
     @Override

modules/parent-join/src/test/java/org/elasticsearch/join/aggregations/ParentToChildrenAggregatorTests.java

@@ -81,6 +81,11 @@ public void testNoDocs() throws IOException {
             assertEquals(Double.POSITIVE_INFINITY, ((InternalMin) parentToChild.getAggregations().get("in_child")).getValue(),
                     Double.MIN_VALUE);
         });
+        testCase(new MatchAllDocsQuery(), newSearcher(indexReader, false, true), parentToChild -> {
+            assertEquals(0, parentToChild.getDocCount());
+            assertEquals(Double.POSITIVE_INFINITY, ((InternalMin) parentToChild.getAggregations().get("in_child")).getValue(),
+                Double.MIN_VALUE);
+        }, null);
         indexReader.close();
         directory.close();
     }
@@ -108,13 +113,29 @@ public void testParentChild() throws IOException {
             assertTrue(JoinAggregationInspectionHelper.hasValue(child));
             assertEquals(expectedMinValue, ((InternalMin) child.getAggregations().get("in_child")).getValue(), Double.MIN_VALUE);
         });
+        testCase(new MatchAllDocsQuery(), indexSearcher, child -> {
+            int expectedTotalChildren = 0;
+            int expectedMinValue = Integer.MAX_VALUE;
+            for (Tuple<Integer, Integer> expectedValues : expectedParentChildRelations.values()) {
+                expectedTotalChildren += expectedValues.v1();
+                expectedMinValue = Math.min(expectedMinValue, expectedValues.v2());
+            }
+            assertEquals(expectedTotalChildren, child.getDocCount());
+            assertTrue(JoinAggregationInspectionHelper.hasValue(child));
+            assertEquals(expectedMinValue, ((InternalMin) child.getAggregations().get("in_child")).getValue(), Double.MIN_VALUE);
+        }, null);
 
         for (String parent : expectedParentChildRelations.keySet()) {
             testCase(new TermInSetQuery(IdFieldMapper.NAME, Uid.encodeId(parent)), indexSearcher, child -> {
                 assertEquals((long) expectedParentChildRelations.get(parent).v1(), child.getDocCount());
                 assertEquals(expectedParentChildRelations.get(parent).v2(),
                         ((InternalMin) child.getAggregations().get("in_child")).getValue(), Double.MIN_VALUE);
             });
+            testCase(new TermInSetQuery(IdFieldMapper.NAME, Uid.encodeId(parent)), indexSearcher, child -> {
+                assertEquals((long) expectedParentChildRelations.get(parent).v1(), child.getDocCount());
+                assertEquals(expectedParentChildRelations.get(parent).v2(),
+                    ((InternalMin) child.getAggregations().get("in_child")).getValue(), Double.MIN_VALUE);
+            }, null);
         }
         indexReader.close();
         directory.close();
@@ -187,4 +208,13 @@ private void testCase(Query query, IndexSearcher indexSearcher, Consumer<Interna
         InternalChildren result = search(indexSearcher, query, aggregationBuilder, fieldType);
         verify.accept(result);
     }
+
+    private void testCase(Query query, IndexSearcher indexSearcher, Consumer<InternalChildren> verify, MappedFieldType fieldType)
+        throws IOException {
+
+        ChildrenAggregationBuilder aggregationBuilder = new ChildrenAggregationBuilder("_name", CHILD_TYPE);
+        aggregationBuilder.subAggregation(new MinAggregationBuilder("in_child").field("number"));
+        InternalChildren result = search(indexSearcher, query, aggregationBuilder, fieldType);
+        verify.accept(result);
+    }
 }