Ensure that _exists queries on keyword fields use norms when they're available.

Author: jtibshirani

server/src/main/java/org/elasticsearch/index/mapper/KeywordFieldMapper.java

@@ -28,6 +28,7 @@
 import org.apache.lucene.index.IndexableField;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.DocValuesFieldExistsQuery;
+import org.apache.lucene.search.NormsFieldExistsQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.util.BytesRef;
@@ -256,8 +257,10 @@ public void setSplitQueriesOnWhitespace(boolean splitQueriesOnWhitespace) {
         public Query existsQuery(QueryShardContext context) {
             if (hasDocValues()) {
                 return new DocValuesFieldExistsQuery(name());
-            } else {
+            } else if (omitNorms()) {
                 return new TermQuery(new Term(FieldNamesFieldMapper.NAME, name()));
+            } else {
+                return new NormsFieldExistsQuery(name());
             }
         }
 

server/src/test/java/org/elasticsearch/index/mapper/KeywordFieldTypeTests.java

@@ -19,7 +19,6 @@
 package org.elasticsearch.index.mapper;
 
 import com.carrotsearch.randomizedtesting.generators.RandomStrings;
-
 import org.apache.lucene.analysis.Analyzer;
 import org.apache.lucene.analysis.LowerCaseFilter;
 import org.apache.lucene.analysis.TokenFilter;
@@ -28,9 +27,11 @@
 import org.apache.lucene.analysis.core.WhitespaceTokenizer;
 import org.apache.lucene.index.IndexOptions;
 import org.apache.lucene.index.Term;
-import org.apache.lucene.search.TermInSetQuery;
+import org.apache.lucene.search.DocValuesFieldExistsQuery;
 import org.apache.lucene.search.FuzzyQuery;
+import org.apache.lucene.search.NormsFieldExistsQuery;
 import org.apache.lucene.search.RegexpQuery;
+import org.apache.lucene.search.TermInSetQuery;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.lucene.Lucene;
@@ -132,6 +133,23 @@ public void testTermsQuery() {
         assertEquals("Cannot search on field [field] since it is not indexed.", e.getMessage());
     }
 
+    public void testExistsQuery() {
+        MappedFieldType ft = createDefaultFieldType();
+        ft.setName("field");
+
+        ft.setHasDocValues(true);
+        ft.setOmitNorms(true);
+        assertEquals(new DocValuesFieldExistsQuery("field"), ft.existsQuery(null));
+
+        ft.setHasDocValues(false);
+        ft.setOmitNorms(false);
+        assertEquals(new NormsFieldExistsQuery("field"), ft.existsQuery(null));
+
+        ft.setHasDocValues(false);
+        ft.setOmitNorms(true);
+        assertEquals(new TermQuery(new Term(FieldNamesFieldMapper.NAME, "field")), ft.existsQuery(null));
+    }
+
     public void testRegexpQuery() {
         MappedFieldType ft = createDefaultFieldType();
         ft.setName("field");