Add parent-aggregation to parent-join module

client/rest-high-level/src/test/java/org/elasticsearch/client/RestHighLevelClientTests.java

@@ -625,7 +625,7 @@ public void testDefaultNamedXContents() {
 
     public void testProvidedNamedXContents() {
         List<NamedXContentRegistry.Entry> namedXContents = RestHighLevelClient.getProvidedNamedXContents();
-        assertEquals(16, namedXContents.size());
+        assertEquals(17, namedXContents.size());
         Map<Class<?>, Integer> categories = new HashMap<>();
         List<String> names = new ArrayList<>();
         for (NamedXContentRegistry.Entry namedXContent : namedXContents) {
@@ -635,8 +635,8 @@ public void testProvidedNamedXContents() {
                 categories.put(namedXContent.categoryClass, counter + 1);
             }
         }
-        assertEquals(4, categories.size());
-        assertEquals(Integer.valueOf(2), categories.get(Aggregation.class));
+        assertEquals("Had: " + categories, 4, categories.size());
+        assertEquals(Integer.valueOf(3), categories.get(Aggregation.class));
         assertTrue(names.contains(ChildrenAggregationBuilder.NAME));
         assertTrue(names.contains(MatrixStatsAggregationBuilder.NAME));
         assertEquals(Integer.valueOf(4), categories.get(EvaluationMetric.class));

docs/reference/aggregations/bucket.asciidoc

@@ -49,6 +49,8 @@ include::bucket/missing-aggregation.asciidoc[]
 
 include::bucket/nested-aggregation.asciidoc[]
 
+include::bucket/parent-aggregation.asciidoc[]
+
 include::bucket/range-aggregation.asciidoc[]
 
 include::bucket/reverse-nested-aggregation.asciidoc[]

docs/reference/aggregations/bucket/parent-aggregation.asciidoc

@@ -0,0 +1,213 @@
+[[search-aggregations-bucket-parent-aggregation]]
+=== Parent Aggregation
+
+A special single bucket aggregation that selects parent documents that have the specified type, as defined in a <<parent-join,`join` field>>.
+
+This aggregation has a single option:
+
+* `type` - The child type that should be selected.
+
+For example, let's say we have an index of questions and answers. The answer type has the following `join` field in the mapping:
+
+[source,js]
+--------------------------------------------------
+PUT parent_example
+{
+  "mappings": {
+    "_doc": {
+      "properties": {
+        "join": {
+          "type": "join",
+          "relations": {
+            "question": "answer"
+          }
+        }
+      }
+    }
+  }
+}
+--------------------------------------------------
+// CONSOLE
+
+The `question` document contain a tag field and the `answer` documents contain an owner field. With the `parent`
+aggregation the owner buckets can be mapped to the tag buckets in a single request even though the two fields exist in
+two different kinds of documents.
+
+An example of a question document:
+
+[source,js]
+--------------------------------------------------
+PUT parent_example/_doc/1
+{
+  "join": {
+    "name": "question"
+  },
+  "body": "<p>I have Windows 2003 server and i bought a new Windows 2008 server...",
+  "title": "Whats the best way to file transfer my site from server to a newer one?",
+  "tags": [
+    "windows-server-2003",
+    "windows-server-2008",
+    "file-transfer"
+  ]
+}
+--------------------------------------------------
+// CONSOLE
+// TEST[continued]
+
+Examples of `answer` documents:
+
+[source,js]
+--------------------------------------------------
+PUT parent_example/_doc/2?routing=1
+{
+  "join": {
+    "name": "answer",
+    "parent": "1"
+  },
+  "owner": {
+    "location": "Norfolk, United Kingdom",
+    "display_name": "Sam",
+    "id": 48
+  },
+  "body": "<p>Unfortunately you're pretty much limited to FTP...",
+  "creation_date": "2009-05-04T13:45:37.030"
+}
+
+PUT parent_example/_doc/3?routing=1&refresh
+{
+  "join": {
+    "name": "answer",
+    "parent": "1"
+  },
+  "owner": {
+    "location": "Norfolk, United Kingdom",
+    "display_name": "Troll",
+    "id": 49
+  },
+  "body": "<p>Use Linux...",
+  "creation_date": "2009-05-05T13:45:37.030"
+}
+--------------------------------------------------
+// CONSOLE
+// TEST[continued]
+
+The following request can be built that connects the two together:
+
+[source,js]
+--------------------------------------------------
+POST parent_example/_search?size=0
+{
+  "aggs": {
+    "top-names": {
+      "terms": {
+        "field": "owner.display_name.keyword",
+        "size": 10
+      },
+      "aggs": {
+        "to-questions": {
+          "parent": {
+            "type" : "answer"
+          },
+          "aggs": {
+            "top-tags": {
+              "terms": {
+                "field": "tags.keyword",
+                "size": 10
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
+--------------------------------------------------
+// CONSOLE
+// TEST[continued]
+
+<1> The `type` points to type / mapping with the name `answer`.
+
+The above example returns the top answer owners and per owner the top question tags.
+
+Possible response:
+
+[source,js]
+--------------------------------------------------
+{
+  "took": 9,
+  "timed_out": false,
+  "_shards": {
+    "total": 1,
+    "successful": 1,
+    "skipped": 0,
+    "failed": 0
+  },
+  "hits": {
+    "total": 3,
+    "max_score": null,
+    "hits": []
+  },
+  "aggregations": {
+    "top-names": {
+      "doc_count_error_upper_bound": 0,
+      "sum_other_doc_count": 0,
+      "buckets": [
+        {
+          "key": "Sam",
+          "doc_count": 1, <1>
+          "to-questions": {
+            "doc_count": 1, <2>
+            "top-tags": {
+              "doc_count_error_upper_bound": 0,
+              "sum_other_doc_count": 0,
+              "buckets": [
+                {
+                  "key": "file-transfer",
+                  "doc_count": 1
+                },
+                {
+                  "key": "windows-server-2003",
+                  "doc_count": 1
+                },
+                {
+                  "key": "windows-server-2008",
+                  "doc_count": 1
+                }
+              ]
+            }
+          }
+        },
+        {
+          "key": "Troll",
+          "doc_count": 1, <1>
+          "to-questions": {
+            "doc_count": 1, <2>
+            "top-tags": {
+              "doc_count_error_upper_bound": 0,
+              "sum_other_doc_count": 0,
+              "buckets": [
+                {
+                  "key": "file-transfer",
+                  "doc_count": 1
+                },
+                {
+                  "key": "windows-server-2003",
+                  "doc_count": 1
+                },
+                {
+                  "key": "windows-server-2008",
+                  "doc_count": 1
+                }
+              ]
+            }
+          }
+        }
+      ]
+    }
+  }
+}
+--------------------------------------------------
+// TESTRESPONSE[s/"took": 9/"took": $body.took/]
+
+<1> The number of answer documents with the tag `Sam`, `Troll`, etc.
+<2> The number of question documents that are related to answer documents with the tag `Sam`, `Troll`, etc.

modules/parent-join/src/main/java/org/elasticsearch/join/ParentJoinPlugin.java

@@ -22,6 +22,8 @@
 import org.elasticsearch.index.mapper.Mapper;
 import org.elasticsearch.join.aggregations.ChildrenAggregationBuilder;
 import org.elasticsearch.join.aggregations.InternalChildren;
+import org.elasticsearch.join.aggregations.InternalParent;
+import org.elasticsearch.join.aggregations.ParentAggregationBuilder;
 import org.elasticsearch.join.mapper.ParentJoinFieldMapper;
 import org.elasticsearch.join.query.HasChildQueryBuilder;
 import org.elasticsearch.join.query.HasParentQueryBuilder;
@@ -51,9 +53,11 @@ public List<QuerySpec<?>> getQueries() {
 
     @Override
     public List<AggregationSpec> getAggregations() {
-        return Collections.singletonList(
-          new AggregationSpec(ChildrenAggregationBuilder.NAME, ChildrenAggregationBuilder::new, ChildrenAggregationBuilder::parse)
-              .addResultReader(InternalChildren::new)
+        return Arrays.asList(
+            new AggregationSpec(ChildrenAggregationBuilder.NAME, ChildrenAggregationBuilder::new, ChildrenAggregationBuilder::parse)
+                .addResultReader(InternalChildren::new),
+            new AggregationSpec(ParentAggregationBuilder.NAME, ParentAggregationBuilder::new, ParentAggregationBuilder::parse)
+                .addResultReader(InternalParent::new)
         );
     }
 

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

@@ -0,0 +1,60 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.join.aggregations;
+
+import org.apache.lucene.search.Query;
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.search.aggregations.Aggregator;
+import org.elasticsearch.search.aggregations.AggregatorFactories;
+import org.elasticsearch.search.aggregations.InternalAggregation;
+import org.elasticsearch.search.aggregations.bucket.BucketsAggregator;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+import org.elasticsearch.search.aggregations.support.ValuesSource;
+import org.elasticsearch.search.internal.SearchContext;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A {@link BucketsAggregator} which resolves to the matching parent documents.
+ */
+public class ChildrenToParentAggregator extends ParentJoinAggregator {
+
+    static final ParseField TYPE_FIELD = new ParseField("type");
+
+    public ChildrenToParentAggregator(String name, AggregatorFactories factories,
+            SearchContext context, Aggregator parent, Query childFilter,
+            Query parentFilter, ValuesSource.Bytes.WithOrdinals valuesSource,
+            long maxOrd, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) throws IOException {
+        super(name, factories, context, parent, childFilter, parentFilter, valuesSource, maxOrd, pipelineAggregators, metaData);
+    }
+
+    @Override
+    public InternalAggregation buildAggregation(long owningBucketOrdinal) throws IOException {
+        return new InternalParent(name, bucketDocCount(owningBucketOrdinal),
+                bucketAggregations(owningBucketOrdinal), pipelineAggregators(), metaData());
+    }
+
+    @Override
+    public InternalAggregation buildEmptyAggregation() {
+        return new InternalParent(name, 0, buildEmptySubAggregations(), pipelineAggregators(),
+                metaData());
+    }
+}

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

@@ -0,0 +1,56 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.join.aggregations;
+
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.search.aggregations.InternalAggregations;
+import org.elasticsearch.search.aggregations.bucket.InternalSingleBucketAggregation;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Results of the {@link ChildrenToParentAggregator}.
+ */
+public class InternalParent extends InternalSingleBucketAggregation implements Parent {
+    public InternalParent(String name, long docCount, InternalAggregations aggregations, List<PipelineAggregator> pipelineAggregators,
+            Map<String, Object> metaData) {
+        super(name, docCount, aggregations, pipelineAggregators, metaData);
+    }
+
+    /**
+     * Read from a stream.
+     */
+    public InternalParent(StreamInput in) throws IOException {
+        super(in);
+    }
+
+    @Override
+    public String getWriteableName() {
+        return ParentAggregationBuilder.NAME;
+    }
+
+    @Override
+    protected InternalSingleBucketAggregation newAggregation(String name, long docCount, InternalAggregations subAggregations) {
+        return new InternalParent(name, docCount, subAggregations, pipelineAggregators(), getMetaData());
+    }
+}

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

@@ -26,4 +26,11 @@ public abstract class JoinAggregationBuilders {
     public static ChildrenAggregationBuilder children(String name, String childType) {
         return new ChildrenAggregationBuilder(name, childType);
     }
+
+    /**
+     * Create a new {@link Parent} aggregation with the given name.
+     */
+    public static ParentAggregationBuilder parent(String name, String childType) {
+        return new ParentAggregationBuilder(name, childType);
+    }
 }