Exclude unmapped fields from query max_clause limit (#49523)

Take into account of number of unmapped fields when calculating against limit. 
Closes #49002

Author: zacharymorn

server/src/main/java/org/elasticsearch/index/search/QueryParserHelper.java

@@ -87,8 +87,8 @@ public static Map<String, Float> resolveMappingFields(QueryShardContext context,
             boolean allField = Regex.isMatchAllPattern(fieldEntry.getKey());
             boolean multiField = Regex.isSimpleMatchPattern(fieldEntry.getKey());
             float weight = fieldEntry.getValue() == null ? 1.0f : fieldEntry.getValue();
-            Map<String, Float> fieldMap = resolveMappingField(context, fieldEntry.getKey(), weight,
-                !multiField, !allField, fieldSuffix);
+            Map<String, Float> fieldMap = resolveMappingField(context, fieldEntry.getKey(), weight, !multiField, !allField, fieldSuffix);
+
             for (Map.Entry<String, Float> field : fieldMap.entrySet()) {
                 float boost = field.getValue();
                 if (resolvedFields.containsKey(field.getKey())) {
@@ -97,6 +97,7 @@ public static Map<String, Float> resolveMappingFields(QueryShardContext context,
                 resolvedFields.put(field.getKey(), boost);
             }
         }
+
         checkForTooManyFields(resolvedFields, context);
         return resolvedFields;
     }
@@ -141,8 +142,6 @@ public static Map<String, Float> resolveMappingField(QueryShardContext context,
 
             MappedFieldType fieldType = context.getMapperService().fullName(fieldName);
             if (fieldType == null) {
-                // Note that we don't ignore unmapped fields.
-                fields.put(fieldName, weight);
                 continue;
             }
 

server/src/test/java/org/elasticsearch/search/query/QueryStringIT.java

@@ -295,6 +295,35 @@ public void testLimitOnExpandedFields() throws Exception {
                         + (CLUSTER_MAX_CLAUSE_COUNT + 1)));
     }
 
+    // The only expectation for this test is to not throw exception
+    public void testLimitOnExpandedFieldsButIgnoreUnmappedFields() throws Exception {
+        XContentBuilder builder = jsonBuilder();
+        builder.startObject();
+        builder.startObject("_doc");
+        builder.startObject("properties");
+        for (int i = 0; i < CLUSTER_MAX_CLAUSE_COUNT; i++) {
+            builder.startObject("field" + i).field("type", "text").endObject();
+        }
+        builder.endObject(); // properties
+        builder.endObject(); // type1
+        builder.endObject();
+
+        assertAcked(prepareCreate("ignoreunmappedfields").setMapping(builder));
+
+        client().prepareIndex("ignoreunmappedfields").setId("1").setSource("field1", "foo bar baz").get();
+        refresh();
+
+        QueryStringQueryBuilder qb = queryStringQuery("bar");
+        if (randomBoolean()) {
+            qb.field("*")
+                .field("unmappedField1")
+                .field("unmappedField2")
+                .field("unmappedField3")
+                .field("unmappedField4");
+        }
+        client().prepareSearch("ignoreunmappedfields").setQuery(qb).get();
+    }
+
     public void testFieldAlias() throws Exception {
         List<IndexRequestBuilder> indexRequests = new ArrayList<>();
         indexRequests.add(client().prepareIndex("test").setId("1").setSource("f3", "text", "f2", "one"));