Return nothing instead of everything in MLT if no field is supported.

Today due the optimizations in the boolean query builder we adjust
a pure negative query with a 'match_all'. This is not the desired
behavior in the MLT API if all the fields in a document are unsupported.
If that happens today we return all documents but the one MLT is
executed on.

Closes #3453

src/main/java/org/elasticsearch/action/mlt/TransportMoreLikeThisAction.java

@@ -183,6 +183,7 @@ public class TransportMoreLikeThisAction extends TransportAction<MoreLikeThisReq
                     // exclude myself
                     Term uidTerm = docMapper.uidMapper().term(request.type(), request.id());
                     boolBuilder.mustNot(termQuery(uidTerm.field(), uidTerm.text()));
+                    boolBuilder.adjustPureNegative(false);
                 } catch (Throwable e) {
                     listener.onFailure(e);
                     return;

src/main/java/org/elasticsearch/index/query/BoolQueryBuilder.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.index.query;
 
+import org.apache.lucene.search.MatchAllDocsQuery;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -41,6 +42,8 @@ public class BoolQueryBuilder extends BaseQueryBuilder implements BoostableQuery
     private Boolean disableCoord;
 
     private String minimumShouldMatch;
+    
+    private Boolean adjustPureNegative;
 
     /**
      * Adds a query that <b>must</b> appear in the matching documents.
@@ -119,6 +122,16 @@ public class BoolQueryBuilder extends BaseQueryBuilder implements BoostableQuery
     public boolean hasClauses() {
         return !mustClauses.isEmpty() || !mustNotClauses.isEmpty() || !shouldClauses.isEmpty();
     }
+    
+    /**
+     * If a boolean query contains only negative ("must not") clauses should the
+     * BooleanQuery be enhanced with a {@link MatchAllDocsQuery} in order to act
+     * as a pure exclude. The default is <code>true</code>.
+     */
+    public BoolQueryBuilder adjustPureNegative(boolean adjustPureNegative) {
+        this.adjustPureNegative = adjustPureNegative;
+        return this;
+    }
 
     @Override
     protected void doXContent(XContentBuilder builder, Params params) throws IOException {
@@ -135,6 +148,9 @@ public class BoolQueryBuilder extends BaseQueryBuilder implements BoostableQuery
         if (minimumShouldMatch != null) {
             builder.field("minimum_should_match", minimumShouldMatch);
         }
+        if (adjustPureNegative != null) {
+            builder.field("adjust_pure_negative", adjustPureNegative);
+        }
         builder.endObject();
     }
 

src/main/java/org/elasticsearch/index/query/BoolQueryParser.java

@@ -60,7 +60,7 @@ public class BoolQueryParser implements QueryParser {
         String minimumShouldMatch = null;
 
         List<BooleanClause> clauses = newArrayList();
-
+        boolean adjustPureNegative = true;
         String currentFieldName = null;
         XContentParser.Token token;
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
@@ -119,6 +119,8 @@ public class BoolQueryParser implements QueryParser {
                     boost = parser.floatValue();
                 } else if ("minimum_number_should_match".equals(currentFieldName) || "minimumNumberShouldMatch".equals(currentFieldName)) {
                     minimumShouldMatch = parser.textOrNull();
+                } else if ("adjust_pure_negative".equals(currentFieldName) || "adjustPureNegative".equals(currentFieldName)) {
+                    adjustPureNegative = parser.booleanValue();
                 } else {
                     throw new QueryParsingException(parseContext.index(), "[bool] query does not support [" + currentFieldName + "]");
                 }
@@ -135,6 +137,6 @@ public class BoolQueryParser implements QueryParser {
         }
         query.setBoost(boost);
         Queries.applyMinimumShouldMatch(query, minimumShouldMatch);
-        return optimizeQuery(fixNegativeQueryIfNeeded(query));
+        return optimizeQuery(adjustPureNegative ? fixNegativeQueryIfNeeded(query) : query);
     }
 }

src/test/java/org/elasticsearch/test/integration/mlt/MoreLikeThisActionTests.java

@@ -58,6 +58,27 @@ public class MoreLikeThisActionTests extends AbstractSharedClusterTest {
         SearchResponse mltResponse = client().moreLikeThis(moreLikeThisRequest("test").type("type1").id("1").minTermFreq(1).minDocFreq(1)).actionGet();
         assertHitCount(mltResponse, 1l);
     }
+    
+    
+    @Test
+    public void testSimpleMoreLikeOnLongField() throws Exception {
+        logger.info("Creating index test");
+        createIndex("test");
+        logger.info("Running Cluster Health");
+        assertThat(ensureGreen(), equalTo(ClusterHealthStatus.GREEN));
+
+        logger.info("Indexing...");
+        client().index(indexRequest("test").type("type1").id("1").source(jsonBuilder().startObject().field("some_long", 1367484649580l).endObject())).actionGet();
+        client().index(indexRequest("test").type("type2").id("2").source(jsonBuilder().startObject().field("some_long", 0).endObject())).actionGet();
+        client().index(indexRequest("test").type("type1").id("3").source(jsonBuilder().startObject().field("some_long", -666).endObject())).actionGet();
+
+
+        client().admin().indices().refresh(refreshRequest()).actionGet();
+
+        logger.info("Running moreLikeThis");
+        SearchResponse mltResponse = client().moreLikeThis(moreLikeThisRequest("test").type("type1").id("1").minTermFreq(1).minDocFreq(1)).actionGet();
+        assertHitCount(mltResponse, 0l);
+    }
 
 
     @Test