diff --git a/README.md b/README.md
index 2f54a32..3e97d65 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # Advanced Object Search via Elasticsearch
 
 Advanced Object Search bundle provides advanced object search in 
-Pimcore backend powered by Elasticsearch. 
+Pimcore backend powered by Elasticsearch v6. 
 
 ## Integration into Pimcore
 
@@ -204,3 +204,7 @@ with Pimcore < 5.4, please add following rewrite rule to your `.htaccess`.
     # rewrite rule for pre pimcore 5.4 core static files
     RewriteRule ^bundles/pimcoreadmin/(.*) /pimcore/static6/$1 [PT,L]
 ``` 
+
+
+## Supported Elastic Search Versions
+- ElasticSearch 6
\ No newline at end of file
diff --git a/src/Filter/FieldDefinitionAdapter/DefaultAdapter.php b/src/Filter/FieldDefinitionAdapter/DefaultAdapter.php
index 00ff353..0bc91ce 100644
--- a/src/Filter/FieldDefinitionAdapter/DefaultAdapter.php
+++ b/src/Filter/FieldDefinitionAdapter/DefaultAdapter.php
@@ -84,15 +84,15 @@ public function getESMapping() {
                 [
                     'properties' => [
                         self::ES_MAPPING_PROPERTY_STANDARD => [
-                            'type' => 'string',
+                            'type' => 'text',
                             'fields' => [
-                                "raw" =>  [ "type" => "string", "index" => "not_analyzed" ]
+                                'raw' =>  [ 'type' => 'keyword' ]
                             ]
                         ],
                         self::ES_MAPPING_PROPERTY_NOT_INHERITED => [
-                            'type' => 'string',
+                            'type' => 'text',
                             'fields' => [
-                                "raw" =>  [ "type" => "string", "index" => "not_analyzed" ]
+                                'raw' =>  [ 'type' => 'keyword' ]
                             ]
                         ]
                     ]
@@ -102,9 +102,9 @@ public function getESMapping() {
             return [
                 $this->fieldDefinition->getName(),
                 [
-                    'type' => 'string',
+                    'type' => 'text',
                     'fields' => [
-                        "raw" =>  [ "type" => "string", "index" => "not_analyzed" ]
+                        'raw' =>  [ 'type' => 'keyword' ]
                     ]
                 ]
             ];
diff --git a/src/Filter/FieldDefinitionAdapter/ManyToOneRelation.php b/src/Filter/FieldDefinitionAdapter/ManyToOneRelation.php
index 6387c1c..0b70992 100644
--- a/src/Filter/FieldDefinitionAdapter/ManyToOneRelation.php
+++ b/src/Filter/FieldDefinitionAdapter/ManyToOneRelation.php
@@ -46,16 +46,16 @@ public function getESMapping() {
                         self::ES_MAPPING_PROPERTY_STANDARD => [
                             'type' => 'nested',
                             'properties' => [
-                                'type' =>  ["type" => "string", "index" => "not_analyzed"],
-                                'subtype' =>  ["type" => "string", "index" => "not_analyzed"],
+                                'type' => ['type' => 'keyword'],
+                                'subtype' => ['type' => 'keyword'],
                                 'id' => ["type" => "long"]
                             ]
                         ],
                         self::ES_MAPPING_PROPERTY_NOT_INHERITED => [
                             'type' => 'nested',
                             'properties' => [
-                                'type' =>  ["type" => "string", "index" => "not_analyzed"],
-                                'subtype' =>  ["type" => "string", "index" => "not_analyzed"],
+                                'type' => ['type' => 'keyword'],
+                                'subtype' => ['type' => 'keyword'],
                                 'id' => ["type" => "long"]
                             ]
                         ]
@@ -68,8 +68,8 @@ public function getESMapping() {
                 [
                     'type' => 'nested',
                     'properties' => [
-                        'type' =>  ["type" => "string", "index" => "not_analyzed"],
-                        'subtype' =>  ["type" => "string", "index" => "not_analyzed"],
+                        'type' => ['type' => 'keyword'],
+                        'subtype' => ['type' => 'keyword'],
                         'id' => ["type" => "long"]
                     ]
                 ]
diff --git a/src/Filter/FieldDefinitionAdapter/Select.php b/src/Filter/FieldDefinitionAdapter/Select.php
index ae78d51..53f562e 100644
--- a/src/Filter/FieldDefinitionAdapter/Select.php
+++ b/src/Filter/FieldDefinitionAdapter/Select.php
@@ -39,14 +39,8 @@ public function getESMapping() {
                 $this->fieldDefinition->getName(),
                 [
                     'properties' => [
-                        self::ES_MAPPING_PROPERTY_STANDARD => [
-                            'type' => 'string',
-                            'index' => 'not_analyzed'
-                        ],
-                        self::ES_MAPPING_PROPERTY_NOT_INHERITED => [
-                            'type' => 'string',
-                            'index' => 'not_analyzed'
-                        ]
+                        self::ES_MAPPING_PROPERTY_STANDARD => ['type' => 'keyword'],
+                        self::ES_MAPPING_PROPERTY_NOT_INHERITED => ['type' => 'keyword']
                     ]
                 ]
             ];
@@ -54,8 +48,7 @@ public function getESMapping() {
             return [
                 $this->fieldDefinition->getName(),
                 [
-                    'type' => 'string',
-                    'index' => 'not_analyzed'
+                    'type' => 'keyword',
                 ]
             ];
         }
diff --git a/src/Service.php b/src/Service.php
index 1733cac..3fe89f0 100644
--- a/src/Service.php
+++ b/src/Service.php
@@ -147,9 +147,9 @@ public function generateMapping(ClassDefinition $objectClass) {
         $mappingProperties = [
             "o_id" => ["type" => "long"],
             "o_checksum" => ["type" => "long"],
-            "type" => ["type" => "string", "index" => "not_analyzed"],
-            "key" =>  ["type" => "string", "index" => "not_analyzed"],
-            "path" => ["type" => "string", "index" => "not_analyzed"]
+            "type" => ["type" => "keyword"],
+            "key" =>  ["type" => "keyword"],
+            "path" => ["type" => "keyword"]
         ];
 
         foreach($fieldDefinitions as $fieldDefinition) {
@@ -171,7 +171,6 @@ public function generateMapping(ClassDefinition $objectClass) {
             ]
         ];
 
-
         return $mappingParams;
 
     }