Adding yml test for keyword fields with doc_values enabled

Signed-off-by: Harsha Vamsi Kalluri <[email protected]>

rest-api-spec/src/main/resources/rest-api-spec/test/search/340_keyword_doc_values.yml

@@ -0,0 +1,46 @@
+---
+"search on keyword fields with doc_values enabled":
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            properties:
+              "some_keyword":
+                type: "keyword"
+                index: true
+                doc_values: true
+
+  - do:
+      bulk:
+        index: test
+        refresh: true
+        body:
+          - '{"index": {"_index": "test", "_id": "1" }}'
+          - '{ "some_keyword": "ingesting some random keyword data" }'
+          - '{ "index": { "_index": "test", "_id": "2" }}'
+          - '{ "some_keyword": "400" }'
+          - '{ "index": { "_index": "test", "_id": "3" } }'
+          - '{ "some_keyword": "5" }'
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            prefix:
+              some_keyword: "ing"
+
+  - match: { hits.hits.0._source.some_keyword: "ingesting some random keyword data" }
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            range: {
+              "some_keyword": {
+                "lt": 500
+              } }
+
+  - match: { hits.total.value: 2 }

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

@@ -42,6 +42,7 @@
 import org.apache.lucene.search.FuzzyQuery;
 import org.apache.lucene.search.IndexOrDocValuesQuery;
 import org.apache.lucene.search.MultiTermQuery;
+import org.apache.lucene.search.PrefixQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.RegexpQuery;
 import org.apache.lucene.search.TermInSetQuery;
@@ -433,7 +434,13 @@ public Query prefixQuery(
                 return new IndexOrDocValuesQuery(indexQuery, dvQuery);
             }
             if (hasDocValues()) {
-                return super.prefixQuery(value, MultiTermQuery.DOC_VALUES_REWRITE, caseInsensitive, context);
+                if (caseInsensitive) {
+                    return AutomatonQueries.caseInsensitivePrefixQuery(
+                        (new Term(name(), indexedValueForSearch(value))),
+                        MultiTermQuery.DOC_VALUES_REWRITE
+                    );
+                }
+                return new PrefixQuery(new Term(name(), indexedValueForSearch(value)), MultiTermQuery.DOC_VALUES_REWRITE);
             }
             return super.prefixQuery(value, method, caseInsensitive, context);
         }