Search: When sorting, allow to pass `track_scores` and set it to `true` to get scores/max_score back, closes #662.

modules/elasticsearch/src/main/java/org/elasticsearch/client/action/search/SearchRequestBuilder.java

@@ -350,6 +350,15 @@ public class SearchRequestBuilder extends BaseRequestBuilder<SearchRequest, Sear
         return this;
     }
 
+    /**
+     * Applies when sorting, and controls if scores will be tracked as well. Defaults to
+     * <tt>false</tt>.
+     */
+    public SearchRequestBuilder setTrackScores(boolean trackScores) {
+        sourceBuilder().trackScores(trackScores);
+        return this;
+    }
+
     /**
      * Adds the fields to load and return as part of the search request. If none are specified,
      * the source of the document will be returned.

modules/elasticsearch/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -84,6 +84,8 @@ public class SearchSourceBuilder implements ToXContent {
 
     private List<SortBuilder> sorts;
 
+    private boolean trackScores = false;
+
     private List<String> fieldNames;
 
     private List<ScriptField> scriptFields;
@@ -219,6 +221,15 @@ public class SearchSourceBuilder implements ToXContent {
         return this;
     }
 
+    /**
+     * Applies when sorting, and controls if scores will be tracked as well. Defaults to
+     * <tt>false</tt>.
+     */
+    public SearchSourceBuilder trackScores(boolean trackScores) {
+        this.trackScores = trackScores;
+        return this;
+    }
+
     /**
      * Add a facet to perform as part of the search.
      */
@@ -453,6 +464,9 @@ public class SearchSourceBuilder implements ToXContent {
                 builder.endObject();
             }
             builder.endArray();
+            if (trackScores) {
+                builder.field("track_scores", trackScores);
+            }
         }
 
         if (indexBoost != null) {

modules/elasticsearch/src/main/java/org/elasticsearch/search/internal/ContextIndexSearcher.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.search.internal;
 
+import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.search.*;
 import org.elasticsearch.common.collect.Lists;
 import org.elasticsearch.common.collect.Maps;
@@ -43,7 +44,9 @@ public class ContextIndexSearcher extends ExtendedIndexSearcher {
         public static final String NA = "_na_";
     }
 
-    private SearchContext searchContext;
+    private final SearchContext searchContext;
+
+    private final IndexReader reader;
 
     private CachedDfSource dfSource;
 
@@ -54,6 +57,7 @@ public class ContextIndexSearcher extends ExtendedIndexSearcher {
     public ContextIndexSearcher(SearchContext searchContext, Engine.Searcher searcher) {
         super(searcher.searcher());
         this.searchContext = searchContext;
+        this.reader = searcher.searcher().getIndexReader();
     }
 
     public void dfSource(CachedDfSource dfSource) {
@@ -116,6 +120,18 @@ public class ContextIndexSearcher extends ExtendedIndexSearcher {
         return query.weight(dfSource);
     }
 
+    // override from the Searcher to allow to control if scores will be tracked or not
+    @Override public TopFieldDocs search(Weight weight, Filter filter, int nDocs,
+                                         Sort sort, boolean fillFields) throws IOException {
+
+        nDocs = Math.min(nDocs, reader.maxDoc());
+
+        TopFieldCollector collector = TopFieldCollector.create(sort, nDocs,
+                fillFields, searchContext.trackScores(), searchContext.trackScores(), !weight.scoresDocsOutOfOrder());
+        search(weight, filter, collector);
+        return (TopFieldDocs) collector.topDocs();
+    }
+
     @Override public void search(Weight weight, Filter filter, Collector collector) throws IOException {
         if (searchContext.parsedFilter() != null) {
             // this will only get applied to the actual search collector and not

modules/elasticsearch/src/main/java/org/elasticsearch/search/internal/SearchContext.java

@@ -110,6 +110,8 @@ public class SearchContext implements Releasable {
 
     private Sort sort;
 
+    private boolean trackScores = false; // when sorting, track scores as well...
+
     private String queryParserName;
 
     private ParsedQuery originalQuery;
@@ -294,6 +296,15 @@ public class SearchContext implements Releasable {
         return this.sort;
     }
 
+    public SearchContext trackScores(boolean trackScores) {
+        this.trackScores = trackScores;
+        return this;
+    }
+
+    public boolean trackScores() {
+        return this.trackScores;
+    }
+
     public SearchContext parsedFilter(Filter filter) {
         this.filter = filter;
         return this;

modules/elasticsearch/src/main/java/org/elasticsearch/search/query/QueryPhase.java

@@ -33,6 +33,7 @@ import org.elasticsearch.search.internal.ContextIndexSearcher;
 import org.elasticsearch.search.internal.ScopePhase;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.search.sort.SortParseElement;
+import org.elasticsearch.search.sort.TrackScoresParseElement;
 
 import java.util.Map;
 
@@ -61,6 +62,8 @@ public class QueryPhase implements SearchPhase {
                 .put("filterBinary", new FilterBinaryParseElement())
                 .put("filter_binary", new FilterBinaryParseElement())
                 .put("sort", new SortParseElement())
+                .put("trackScores", new TrackScoresParseElement())
+                .put("track_scores", new TrackScoresParseElement())
                 .putAll(facetPhase.parseElements());
         return parseElements.build();
     }

modules/elasticsearch/src/main/java/org/elasticsearch/search/sort/TrackScoresParseElement.java

@@ -0,0 +1,37 @@
+/*
+ * Licensed to Elastic Search and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Elastic Search 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.search.sort;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.SearchParseElement;
+import org.elasticsearch.search.internal.SearchContext;
+
+/**
+ * @author kimchy (shay.banon)
+ */
+public class TrackScoresParseElement implements SearchParseElement {
+
+    @Override public void parse(XContentParser parser, SearchContext context) throws Exception {
+        XContentParser.Token token = parser.currentToken();
+        if (token.isValue()) {
+            context.trackScores(parser.booleanValue());
+        }
+    }
+}

modules/test/integration/src/test/java/org/elasticsearch/test/integration/search/sort/SimpleSortTests.java

@@ -22,12 +22,15 @@ package org.elasticsearch.test.integration.search.sort;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.ShardSearchFailure;
 import org.elasticsearch.client.Client;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.search.sort.SortOrder;
 import org.elasticsearch.test.integration.AbstractNodesTests;
 import org.testng.annotations.AfterClass;
 import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
 
+import static org.elasticsearch.common.settings.ImmutableSettings.*;
 import static org.elasticsearch.common.xcontent.XContentFactory.*;
 import static org.elasticsearch.index.query.xcontent.QueryBuilders.*;
 import static org.elasticsearch.search.sort.SortBuilders.*;
@@ -42,8 +45,9 @@ public class SimpleSortTests extends AbstractNodesTests {
     private Client client;
 
     @BeforeClass public void createNodes() throws Exception {
-        startNode("server1");
+        Settings settings = settingsBuilder().put("number_of_shards", 3).put("number_of_replicas", 0).build();
-        startNode("server2");
+        startNode("server1", settings);
+        startNode("server2", settings);
         client = getClient();
     }
 
@@ -56,6 +60,54 @@ public class SimpleSortTests extends AbstractNodesTests {
         return client("server1");
     }
 
+    @Test public void testTrackScores() throws Exception {
+        try {
+            client.admin().indices().prepareDelete("test").execute().actionGet();
+        } catch (Exception e) {
+            // ignore
+        }
+        client.admin().indices().prepareCreate("test").execute().actionGet();
+        client.admin().cluster().prepareHealth().setWaitForGreenStatus().execute().actionGet();
+
+        client.prepareIndex("test", "type1").setSource(jsonBuilder().startObject()
+                .field("id", "1")
+                .field("svalue", "aaa")
+                .field("ivalue", 100)
+                .field("dvalue", 0.1)
+                .endObject()).execute().actionGet();
+
+        client.prepareIndex("test", "type1").setSource(jsonBuilder().startObject()
+                .field("id", "2")
+                .field("svalue", "bbb")
+                .field("ivalue", 200)
+                .field("dvalue", 0.2)
+                .endObject()).execute().actionGet();
+
+        client.admin().indices().prepareFlush().setRefresh(true).execute().actionGet();
+
+        SearchResponse searchResponse = client.prepareSearch()
+                .setQuery(matchAllQuery())
+                .addSort("svalue", SortOrder.ASC)
+                .execute().actionGet();
+
+        assertThat(searchResponse.hits().getMaxScore(), equalTo(Float.NaN));
+        for (SearchHit hit : searchResponse.hits()) {
+            assertThat(hit.getScore(), equalTo(Float.NaN));
+        }
+
+        // now check with score tracking
+        searchResponse = client.prepareSearch()
+                .setQuery(matchAllQuery())
+                .addSort("svalue", SortOrder.ASC)
+                .setTrackScores(true)
+                .execute().actionGet();
+
+        assertThat(searchResponse.hits().getMaxScore(), not(equalTo(Float.NaN)));
+        for (SearchHit hit : searchResponse.hits()) {
+            assertThat(hit.getScore(), not(equalTo(Float.NaN)));
+        }
+    }
+
     @Test public void testSimpleSorts() throws Exception {
         try {
             client.admin().indices().prepareDelete("test").execute().actionGet();

modules/test/integration/src/test/java/org/elasticsearch/test/integration/search/sort/SimpleSortTests.yml

@@ -1,7 +0,0 @@
-cluster:
-  routing:
-    schedule: 100ms
-index:
-  number_of_shards: 3
-  number_of_replicas: 0
-  routing :