Search: Allow to filter out docs based on a minimum score, closes #719.

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

@@ -229,6 +229,14 @@ public class SearchRequestBuilder extends BaseRequestBuilder<SearchRequest, Sear
         return this;
     }
 
+    /**
+     * Sets the minimum score below which docs will be filtered out.
+     */
+    public SearchRequestBuilder setMinScore(float minScore) {
+        sourceBuilder().minScore(minScore);
+        return this;
+    }
+
     /**
      * From index to start the search from. Defaults to <tt>0</tt>.
      */

modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/MinimumScoreCollector.java

@@ -0,0 +1,66 @@
+/*
+ * 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.common.lucene;
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.search.Collector;
+import org.apache.lucene.search.ScoreCachingWrappingScorer;
+import org.apache.lucene.search.Scorer;
+
+import java.io.IOException;
+
+/**
+ *
+ */
+public class MinimumScoreCollector extends Collector {
+
+    private final Collector collector;
+
+    private final float minimumScore;
+
+    private Scorer scorer;
+
+    public MinimumScoreCollector(Collector collector, float minimumScore) {
+        this.collector = collector;
+        this.minimumScore = minimumScore;
+    }
+
+    @Override public void setScorer(Scorer scorer) throws IOException {
+        if (!(scorer instanceof ScoreCachingWrappingScorer)) {
+            scorer = new ScoreCachingWrappingScorer(scorer);
+        }
+        this.scorer = scorer;
+        collector.setScorer(scorer);
+    }
+
+    @Override public void collect(int doc) throws IOException {
+        if (scorer.score() > minimumScore) {
+            collector.collect(doc);
+        }
+    }
+
+    @Override public void setNextReader(IndexReader reader, int docBase) throws IOException {
+        collector.setNextReader(reader, docBase);
+    }
+
+    @Override public boolean acceptsDocsOutOfOrder() {
+        return collector.acceptsDocsOutOfOrder();
+    }
+}

modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/MultiCollector.java

@@ -41,7 +41,8 @@ public class MultiCollector extends Collector {
     }
 
     @Override public void setScorer(Scorer scorer) throws IOException {
-        if (collectors.length > 0) {
+        // always wrap it in a scorer wrapper
+        if (!(scorer instanceof ScoreCachingWrappingScorer)) {
             scorer = new ScoreCachingWrappingScorer(scorer);
         }
         collector.setScorer(scorer);

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

@@ -88,6 +88,8 @@ public class SearchSourceBuilder implements ToXContent {
 
     private boolean trackScores = false;
 
+    private Float minScore;
+
     private List<String> fieldNames;
 
     private List<ScriptField> scriptFields;
@@ -176,6 +178,14 @@ public class SearchSourceBuilder implements ToXContent {
         return this;
     }
 
+    /**
+     * Sets the minimum score below which docs will be filtered out.
+     */
+    public SearchSourceBuilder minScore(float minScore) {
+        this.minScore = minScore;
+        return this;
+    }
+
     /**
      * An optional query parser name to use.
      */
@@ -434,6 +444,10 @@ public class SearchSourceBuilder implements ToXContent {
             }
         }
 
+        if (minScore != null) {
+            builder.field("min_score", minScore);
+        }
+
         if (version != null) {
             builder.field("version", version);
         }

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

@@ -23,6 +23,7 @@ import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.search.*;
 import org.elasticsearch.common.collect.Lists;
 import org.elasticsearch.common.collect.Maps;
+import org.elasticsearch.common.lucene.MinimumScoreCollector;
 import org.elasticsearch.common.lucene.MultiCollector;
 import org.elasticsearch.common.lucene.search.ExtendedIndexSearcher;
 import org.elasticsearch.common.lucene.search.FilteredCollector;
@@ -147,6 +148,11 @@ public class ContextIndexSearcher extends ExtendedIndexSearcher {
                 collector = new MultiCollector(collector, collectors.toArray(new Collector[collectors.size()]));
             }
         }
+        // apply the minimum score after multi collector so we filter facets as well
+        if (searchContext.minimumScore() != null) {
+            collector = new MinimumScoreCollector(collector, searchContext.minimumScore());
+        }
+
         // we only compute the doc id set once since within a context, we execute the same query always...
         if (searchContext.timeout() != null) {
             searchContext.queryResult().searchTimedOut(false);

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

@@ -115,6 +115,8 @@ public class SearchContext implements Releasable {
 
     private Sort sort;
 
+    private Float minimumScore;
+
     private boolean trackScores = false; // when sorting, track scores as well...
 
     private String queryParserName;
@@ -302,6 +304,15 @@ public class SearchContext implements Releasable {
         return timeout;
     }
 
+    public SearchContext minimumScore(float minimumScore) {
+        this.minimumScore = minimumScore;
+        return this;
+    }
+
+    public Float minimumScore() {
+        return this.minimumScore;
+    }
+
     public SearchContext sort(Sort sort) {
         this.sort = sort;
         return this;

modules/elasticsearch/src/main/java/org/elasticsearch/search/query/MinScoreParseElement.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.query;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.SearchParseElement;
+import org.elasticsearch.search.internal.SearchContext;
+
+/**
+ * @author kimchy (shay.banon)
+ */
+public class MinScoreParseElement implements SearchParseElement {
+
+    @Override public void parse(XContentParser parser, SearchContext context) throws Exception {
+        XContentParser.Token token = parser.currentToken();
+        if (token.isValue()) {
+            context.minimumScore(parser.floatValue());
+        }
+    }
+}

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

@@ -67,6 +67,8 @@ public class QueryPhase implements SearchPhase {
                 .put("sort", new SortParseElement())
                 .put("trackScores", new TrackScoresParseElement())
                 .put("track_scores", new TrackScoresParseElement())
+                .put("min_score", new MinScoreParseElement())
+                .put("minScore", new MinScoreParseElement())
                 .putAll(facetPhase.parseElements());
         return parseElements.build();
     }