Add parent-join module (#24638)

* Add parent-join module

This change adds a new module named `parent-join`.
The goal of this module is to provide a replacement for the `_parent` field but as a first step this change only moves the `has_child`, `has_parent` queries and the `children` aggregation to this module.
These queries and aggregations are no longer in core but they are deployed by default as a module.

Relates #20257

build.gradle

@@ -122,6 +122,7 @@ subprojects {
     "org.elasticsearch.plugin:transport-netty4-client:${version}": ':modules:transport-netty4',
     "org.elasticsearch.plugin:reindex-client:${version}": ':modules:reindex',
     "org.elasticsearch.plugin:lang-mustache-client:${version}": ':modules:lang-mustache',
+    "org.elasticsearch.plugin:parent-join-client:${version}": ':modules:parent-join',
     "org.elasticsearch.plugin:percolator-client:${version}": ':modules:percolator',
   ]
   configurations.all {

buildSrc/src/main/resources/checkstyle_suppressions.xml

@@ -676,7 +676,6 @@
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]BoolQueryBuilderTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]BoostingQueryBuilderTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]GeoDistanceQueryBuilderTests.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]HasChildQueryBuilderTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]MoreLikeThisQueryBuilderTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]MultiMatchQueryBuilderTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]SpanMultiTermQueryBuilderTests.java" checks="LineLength" />
@@ -745,7 +744,6 @@
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]MultiValueModeTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]SearchWithRejectionsIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]MissingValueIT.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]ChildrenIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]DateHistogramIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]DateHistogramOffsetIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]GeoDistanceIT.java" checks="LineLength" />
@@ -772,7 +770,6 @@
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]basic[/\\]SearchWithRandomExceptionsIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]basic[/\\]SearchWithRandomIOExceptionsIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]basic[/\\]TransportTwoNodesSearchIT.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]child[/\\]ChildQuerySearchIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]child[/\\]ParentFieldLoadingIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]geo[/\\]GeoBoundingBoxIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]geo[/\\]GeoFilterIT.java" checks="LineLength" />

client/transport/build.gradle

@@ -32,6 +32,7 @@ dependencies {
   compile "org.elasticsearch.plugin:reindex-client:${version}"
   compile "org.elasticsearch.plugin:lang-mustache-client:${version}"
   compile "org.elasticsearch.plugin:percolator-client:${version}"
+  compile "org.elasticsearch.plugin:parent-join-client:${version}"
   testCompile "com.carrotsearch.randomizedtesting:randomizedtesting-runner:${versions.randomizedrunner}"
   testCompile "junit:junit:${versions.junit}"
   testCompile "org.hamcrest:hamcrest-all:${versions.hamcrest}"

core/src/main/java/org/elasticsearch/index/query/InnerHitBuilder.java

@@ -195,7 +195,8 @@ private InnerHitBuilder(InnerHitBuilder other) {
         }
     }
 
-    InnerHitBuilder(InnerHitBuilder other, QueryBuilder query, String parentChildType, boolean ignoreUnmapped) {
+    // NORELEASE Do not use this ctr, it is public for hasChild and hasParent query but this is temporary
+    public InnerHitBuilder(InnerHitBuilder other, QueryBuilder query, String parentChildType, boolean ignoreUnmapped) {
         this(other);
         this.query = query;
         this.parentChildType = parentChildType;
@@ -751,7 +752,8 @@ public static void extractInnerHits(QueryBuilder query, Map<String, InnerHitBuil
         }
     }
 
-    static InnerHitBuilder rewrite(InnerHitBuilder original, QueryBuilder rewrittenQuery) {
+    // TODO public for hasParent and hasChild query
+    public static InnerHitBuilder rewrite(InnerHitBuilder original, QueryBuilder rewrittenQuery) {
         if (original == null) {
             return null;
         }

core/src/main/java/org/elasticsearch/index/query/NestedQueryBuilder.java

@@ -23,7 +23,6 @@
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.join.BitSetProducer;
 import org.apache.lucene.search.join.ScoreMode;
-import org.apache.lucene.search.join.ToParentBlockJoinQuery;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -36,6 +35,7 @@
 import org.elasticsearch.index.search.NestedHelper;
 
 import java.io.IOException;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -145,7 +145,7 @@ protected void doXContent(XContentBuilder builder, Params params) throws IOExcep
         builder.field(PATH_FIELD.getPreferredName(), path);
         builder.field(IGNORE_UNMAPPED_FIELD.getPreferredName(), ignoreUnmapped);
         if (scoreMode != null) {
-            builder.field(SCORE_MODE_FIELD.getPreferredName(), HasChildQueryBuilder.scoreModeAsString(scoreMode));
+            builder.field(SCORE_MODE_FIELD.getPreferredName(), scoreModeAsString(scoreMode));
         }
         printBoostAndQueryName(builder);
         if (innerHitBuilder != null) {
@@ -184,7 +184,7 @@ public static Optional<NestedQueryBuilder> fromXContent(QueryParseContext parseC
                 } else if (IGNORE_UNMAPPED_FIELD.match(currentFieldName)) {
                     ignoreUnmapped = parser.booleanValue();
                 } else if (SCORE_MODE_FIELD.match(currentFieldName)) {
-                    scoreMode = HasChildQueryBuilder.parseScoreMode(parser.text());
+                    scoreMode = parseScoreMode(parser.text());
                 } else if (AbstractQueryBuilder.NAME_FIELD.match(currentFieldName)) {
                     queryName = parser.text();
                 } else {
@@ -207,6 +207,30 @@ public static Optional<NestedQueryBuilder> fromXContent(QueryParseContext parseC
         return Optional.of(queryBuilder);
     }
 
+    public static ScoreMode parseScoreMode(String scoreModeString) {
+        if ("none".equals(scoreModeString)) {
+            return ScoreMode.None;
+        } else if ("min".equals(scoreModeString)) {
+            return ScoreMode.Min;
+        } else if ("max".equals(scoreModeString)) {
+            return ScoreMode.Max;
+        } else if ("avg".equals(scoreModeString)) {
+            return ScoreMode.Avg;
+        } else if ("sum".equals(scoreModeString)) {
+            return ScoreMode.Total;
+        }
+        throw new IllegalArgumentException("No score mode for child query [" + scoreModeString + "] found");
+    }
+
+    public static String scoreModeAsString(ScoreMode scoreMode) {
+        if (scoreMode == ScoreMode.Total) {
+            // Lucene uses 'total' but 'sum' is more consistent with other elasticsearch APIs
+            return "sum";
+        } else {
+            return scoreMode.name().toLowerCase(Locale.ROOT);
+        }
+    }
+
     @Override
     public final String getWriteableName() {
         return NAME;

core/src/main/java/org/elasticsearch/index/query/QueryBuilders.java

@@ -471,30 +471,6 @@ public static MoreLikeThisQueryBuilder moreLikeThisQuery(Item[] likeItems) {
         return moreLikeThisQuery(null, null, likeItems);
     }
 
-    /**
-     * Constructs a new has_child query, with the child type and the query to run on the child documents. The
-     * results of this query are the parent docs that those child docs matched.
-     *
-     * @param type      The child type.
-     * @param query     The query.
-     * @param scoreMode How the scores from the children hits should be aggregated into the parent hit.
-     */
-    public static HasChildQueryBuilder hasChildQuery(String type, QueryBuilder query, ScoreMode scoreMode) {
-        return new HasChildQueryBuilder(type, query, scoreMode);
-    }
-
-    /**
-     * Constructs a new parent query, with the parent type and the query to run on the parent documents. The
-     * results of this query are the children docs that those parent docs matched.
-     *
-     * @param type      The parent type.
-     * @param query     The query.
-     * @param score     Whether the score from the parent hit should propogate to the child hit
-     */
-    public static HasParentQueryBuilder hasParentQuery(String type, QueryBuilder query, boolean score) {
-        return new HasParentQueryBuilder(type, query, score);
-    }
-
     /**
      * Constructs a new parent id query that returns all child documents of the specified type that
      * point to the specified id.

core/src/main/java/org/elasticsearch/search/SearchModule.java

@@ -20,8 +20,6 @@
 package org.elasticsearch.search;
 
 import org.apache.lucene.search.BooleanQuery;
-import org.elasticsearch.action.search.SearchRequest;
-import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.common.NamedRegistry;
 import org.elasticsearch.common.geo.ShapesAvailability;
 import org.elasticsearch.common.geo.builders.ShapeBuilders;
@@ -47,8 +45,6 @@
 import org.elasticsearch.index.query.GeoPolygonQueryBuilder;
 import org.elasticsearch.index.query.GeoShapeQueryBuilder;
 import org.elasticsearch.index.query.GeohashCellQuery;
-import org.elasticsearch.index.query.HasChildQueryBuilder;
-import org.elasticsearch.index.query.HasParentQueryBuilder;
 import org.elasticsearch.index.query.IdsQueryBuilder;
 import org.elasticsearch.index.query.IndicesQueryBuilder;
 import org.elasticsearch.index.query.MatchAllQueryBuilder;
@@ -106,8 +102,6 @@
 import org.elasticsearch.search.aggregations.PipelineAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.adjacency.AdjacencyMatrixAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.adjacency.InternalAdjacencyMatrix;
-import org.elasticsearch.search.aggregations.bucket.children.ChildrenAggregationBuilder;
-import org.elasticsearch.search.aggregations.bucket.children.InternalChildren;
 import org.elasticsearch.search.aggregations.bucket.filter.FilterAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.filter.InternalFilter;
 import org.elasticsearch.search.aggregations.bucket.filters.FiltersAggregationBuilder;
@@ -260,7 +254,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -414,9 +407,6 @@ private void registerAggregations(List<SearchPlugin> plugins) {
                 GeoCentroidAggregationBuilder::parse).addResultReader(InternalGeoCentroid::new));
         registerAggregation(new AggregationSpec(ScriptedMetricAggregationBuilder.NAME, ScriptedMetricAggregationBuilder::new,
                 ScriptedMetricAggregationBuilder::parse).addResultReader(InternalScriptedMetric::new));
-        registerAggregation(new AggregationSpec(ChildrenAggregationBuilder.NAME, ChildrenAggregationBuilder::new,
-                ChildrenAggregationBuilder::parse).addResultReader(InternalChildren::new));
-
         registerFromPlugin(plugins, SearchPlugin::getAggregations, this::registerAggregation);
     }
 
@@ -710,8 +700,6 @@ private void registerQueryParsers(List<SearchPlugin> plugins) {
                 MatchPhrasePrefixQueryBuilder::fromXContent));
         registerQuery(new QuerySpec<>(MultiMatchQueryBuilder.NAME, MultiMatchQueryBuilder::new, MultiMatchQueryBuilder::fromXContent));
         registerQuery(new QuerySpec<>(NestedQueryBuilder.NAME, NestedQueryBuilder::new, NestedQueryBuilder::fromXContent));
-        registerQuery(new QuerySpec<>(HasChildQueryBuilder.NAME, HasChildQueryBuilder::new, HasChildQueryBuilder::fromXContent));
-        registerQuery(new QuerySpec<>(HasParentQueryBuilder.NAME, HasParentQueryBuilder::new, HasParentQueryBuilder::fromXContent));
         registerQuery(new QuerySpec<>(DisMaxQueryBuilder.NAME, DisMaxQueryBuilder::new, DisMaxQueryBuilder::fromXContent));
         registerQuery(new QuerySpec<>(IdsQueryBuilder.NAME, IdsQueryBuilder::new, IdsQueryBuilder::fromXContent));
         registerQuery(new QuerySpec<>(MatchAllQueryBuilder.NAME, MatchAllQueryBuilder::new, MatchAllQueryBuilder::fromXContent));

core/src/main/java/org/elasticsearch/search/aggregations/AggregationBuilders.java

@@ -23,8 +23,6 @@
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.search.aggregations.bucket.adjacency.AdjacencyMatrix;
 import org.elasticsearch.search.aggregations.bucket.adjacency.AdjacencyMatrixAggregationBuilder;
-import org.elasticsearch.search.aggregations.bucket.children.Children;
-import org.elasticsearch.search.aggregations.bucket.children.ChildrenAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.filter.Filter;
 import org.elasticsearch.search.aggregations.bucket.filter.FilterAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.filters.Filters;
@@ -163,20 +161,20 @@ public static FiltersAggregationBuilder filters(String name, KeyedFilter... filt
     public static FiltersAggregationBuilder filters(String name, QueryBuilder... filters) {
         return new FiltersAggregationBuilder(name, filters);
     }
-    
+
     /**
      * Create a new {@link AdjacencyMatrix} aggregation with the given name.
      */
     public static AdjacencyMatrixAggregationBuilder adjacencyMatrix(String name, Map<String, QueryBuilder> filters) {
         return new AdjacencyMatrixAggregationBuilder(name, filters);
-    }    
-    
+    }
+
     /**
      * Create a new {@link AdjacencyMatrix} aggregation with the given name and separator
      */
     public static AdjacencyMatrixAggregationBuilder adjacencyMatrix(String name, String separator,  Map<String, QueryBuilder> filters) {
         return new AdjacencyMatrixAggregationBuilder(name, separator, filters);
-    }     
+    }
 
     /**
      * Create a new {@link Sampler} aggregation with the given name.
@@ -220,13 +218,6 @@ public static ReverseNestedAggregationBuilder reverseNested(String name) {
         return new ReverseNestedAggregationBuilder(name);
     }
 
-    /**
-     * Create a new {@link Children} aggregation with the given name.
-     */
-    public static ChildrenAggregationBuilder children(String name, String childType) {
-        return new ChildrenAggregationBuilder(name, childType);
-    }
-
     /**
      * Create a new {@link GeoDistance} aggregation with the given name.
      */

core/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/CustomQueryScorer.java

@@ -26,7 +26,6 @@
 import org.apache.lucene.search.highlight.WeightedSpanTermExtractor;
 import org.elasticsearch.common.lucene.search.function.FiltersFunctionScoreQuery;
 import org.elasticsearch.common.lucene.search.function.FunctionScoreQuery;
-import org.elasticsearch.index.query.HasChildQueryBuilder;
 
 import java.io.IOException;
 import java.util.Map;
@@ -83,7 +82,7 @@ protected void extractUnknownQuery(Query query,
         }
 
         protected void extract(Query query, float boost, Map<String, WeightedSpanTerm> terms) throws IOException {
-            if (query instanceof HasChildQueryBuilder.LateParsingQuery) {
+            if (isChildOrParentQuery(query.getClass())) {
                 // skip has_child or has_parent queries, see: https://github.com/elastic/elasticsearch/issues/14999
                 return;
             } else if (query instanceof FunctionScoreQuery) {
@@ -94,5 +93,13 @@ protected void extract(Query query, float boost, Map<String, WeightedSpanTerm> t
                 super.extract(query, boost, terms);
             }
         }
+
+        /**
+         * Workaround to detect parent/child query
+         */
+        private static final String PARENT_CHILD_QUERY_NAME = "HasChildQueryBuilder$LateParsingQuery";
+        private static boolean isChildOrParentQuery(Class<?> clazz) {
+            return clazz.getName().endsWith(PARENT_CHILD_QUERY_NAME);
+        }
     }
 }