From 0821fa23ffa00d449e9deacf15db0c3331bed360 Mon Sep 17 00:00:00 2001
From: Jim Ferenczi <jim.ferenczi@elastic.co>
Date: Fri, 7 Apr 2017 15:15:43 +0200
Subject: [PATCH] Restore special case for wilcard on _all query to rewrite to
 a match all query (#23967)

This change restores the rewrite to a match all query that we used to apply on wildcard query * on the query_string parser before #23433.
---
 .../lucene/queryparser/classic/MapperQueryParser.java      | 7 ++++++-
 .../index/query/QueryStringQueryBuilderTests.java          | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/org/apache/lucene/queryparser/classic/MapperQueryParser.java b/core/src/main/java/org/apache/lucene/queryparser/classic/MapperQueryParser.java
index c0c48767529..2b592aa935f 100644
--- a/core/src/main/java/org/apache/lucene/queryparser/classic/MapperQueryParser.java
+++ b/core/src/main/java/org/apache/lucene/queryparser/classic/MapperQueryParser.java
@@ -44,6 +44,7 @@ import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.automaton.RegExp;
 import org.elasticsearch.common.lucene.search.Queries;
 import org.elasticsearch.common.unit.Fuzziness;
+import org.elasticsearch.index.mapper.AllFieldMapper;
 import org.elasticsearch.index.mapper.DateFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.MapperService;
@@ -569,7 +570,11 @@ public class MapperQueryParser extends AnalyzingQueryParser {
     @Override
     protected Query getWildcardQuery(String field, String termStr) throws ParseException {
         if (termStr.equals("*") && field != null) {
-            if ("*".equals(field)) {
+            /**
+             * We rewrite _all:* to a match all query.
+             * TODO: We can remove this special case when _all is completely removed.
+             */
+            if ("*".equals(field) || AllFieldMapper.NAME.equals(field)) {
                 return newMatchAllDocsQuery();
             }
             String actualField = field;
diff --git a/core/src/test/java/org/elasticsearch/index/query/QueryStringQueryBuilderTests.java b/core/src/test/java/org/elasticsearch/index/query/QueryStringQueryBuilderTests.java
index 38e23bd5d50..28bc9c83a50 100644
--- a/core/src/test/java/org/elasticsearch/index/query/QueryStringQueryBuilderTests.java
+++ b/core/src/test/java/org/elasticsearch/index/query/QueryStringQueryBuilderTests.java
@@ -822,7 +822,7 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
 
         queryBuilder = new QueryStringQueryBuilder("_all:*");
         query = queryBuilder.toQuery(context);
-        expected = new ConstantScoreQuery(new TermQuery(new Term("_field_names", "_all")));
+        expected = new MatchAllDocsQuery();
         assertThat(query, equalTo(expected));
 
         queryBuilder = new QueryStringQueryBuilder("*:*");