Add index.mapper.source.mode setting that supersedes _source.mode mapping attribute

docs/plugins/mapper-annotated-text.asciidoc

@@ -167,8 +167,10 @@ duplicates removed. So:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "text": {
         "type": "annotated_text",
@@ -215,8 +217,10 @@ are preserved.
 ----
 PUT idx
 {
+  "settings": {
+     "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "text": { "type": "annotated_text", "store": true }
     }

docs/reference/mapping/fields/synthetic-source.asciidoc

@@ -11,16 +11,14 @@ of official GA features.
 Though very handy to have around, the source field takes up a significant amount
 of space on disk. Instead of storing source documents on disk exactly as you
 send them, Elasticsearch can reconstruct source content on the fly upon retrieval.
-Enable this by setting `mode: synthetic` in `_source`:
+Enable this by configuring the `index.mapper.source.mode` index setting to `synthetic`:
 
 [source,console,id=enable-synthetic-source-example]
 ----
 PUT idx
 {
-  "mappings": {
-    "_source": {
-      "mode": "synthetic"
-    }
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
   }
 }
 ----
@@ -41,7 +39,7 @@ For all other field types, the original value of the field is stored as is, in t
 [[synthetic-source-restrictions]]
 ===== Synthetic `_source` restrictions
 
-Synthetic `_source` cannot be used together with field mappings that use <<copy-to,`copy_to`>>. 
+Synthetic `_source` cannot be used together with field mappings that use <<copy-to,`copy_to`>>.
 
 Some field types have additional restrictions. These restrictions are documented in the **synthetic `_source`** section of the field type's <<mapping-types,documentation>>.
 
@@ -164,7 +162,7 @@ Values of `geo_point` fields are represented in synthetic `_source` with reduced
 
 [[synthetic-source-fields-native-list]]
 ===== Field types that support synthetic source with no storage overhead
-The following field types support synthetic source using data from <<doc-values,`doc_values`>> or <<stored-fields, stored fields>>, and require no additional storage space to construct the `_source` field. 
+The following field types support synthetic source using data from <<doc-values,`doc_values`>> or <<stored-fields, stored fields>>, and require no additional storage space to construct the `_source` field.
 
 NOTE: If you enable the <<ignore-malformed,`ignore_malformed`>> or <<ignore-above,`ignore_above`>> settings, then additional storage is required to store ignored field values for these types.
 

docs/reference/mapping/types/aggregate-metric-double.asciidoc

@@ -267,8 +267,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "agg_metric": {
         "type": "aggregate_metric_double",

docs/reference/mapping/types/binary.asciidoc

@@ -68,8 +68,10 @@ of official GA features.
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "binary": { "type": "binary", "doc_values": true }
     }

docs/reference/mapping/types/boolean.asciidoc

@@ -249,8 +249,10 @@ Synthetic source always sorts `boolean` fields. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "bool": { "type": "boolean" }
     }

docs/reference/mapping/types/date.asciidoc

@@ -249,8 +249,10 @@ Synthetic source always sorts `date` fields. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "date": { "type": "date" }
     }

docs/reference/mapping/types/date_nanos.asciidoc

@@ -160,8 +160,10 @@ Synthetic source always sorts `date_nanos` fields. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "date": { "type": "date_nanos" }
     }

docs/reference/mapping/types/flattened.asciidoc

@@ -334,8 +334,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "flattened": { "type": "flattened" }
     }
@@ -367,8 +369,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "flattened": { "type": "flattened" }
     }
@@ -407,8 +411,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "flattened": { "type": "flattened" }
     }

docs/reference/mapping/types/geo-point.asciidoc

@@ -229,8 +229,10 @@ longitude) and reduces them to their stored precision. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "point": { "type": "geo_point" }
     }

docs/reference/mapping/types/ip.asciidoc

@@ -170,8 +170,10 @@ Synthetic source always sorts `ip` fields and removes duplicates. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "ip": { "type": "ip" }
     }

docs/reference/mapping/types/keyword.asciidoc

@@ -188,8 +188,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "kwd": { "type": "keyword" }
     }
@@ -218,8 +220,10 @@ are preserved. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "kwd": { "type": "keyword", "store": true }
     }
@@ -248,8 +252,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "kwd": { "type": "keyword", "ignore_above": 3 }
     }

docs/reference/mapping/types/numeric.asciidoc

@@ -259,8 +259,10 @@ Synthetic source always sorts numeric fields. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "long": { "type": "long" }
     }
@@ -287,8 +289,10 @@ Scaled floats will always apply their scaling factor so:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "f": { "type": "scaled_float", "scaling_factor": 0.01 }
     }

docs/reference/mapping/types/range.asciidoc

@@ -254,8 +254,10 @@ Synthetic source always sorts values and removes duplicates for all `range` fiel
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "my_range": { "type": "long_range" }
     }
@@ -316,8 +318,10 @@ For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "my_range": { "type": "ip_range" }
     }
@@ -357,8 +361,10 @@ Range field vales are always represented as inclusive on both sides with bounds
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "my_range": { "type": "long_range" }
     }
@@ -394,8 +400,10 @@ Default values for range bounds are represented as `null` in synthetic source. T
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "my_range": { "type": "integer_range" }
     }
@@ -429,8 +437,10 @@ Will become:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "my_range": { "type": "date_range" }
     }

docs/reference/mapping/types/text.asciidoc

@@ -184,8 +184,10 @@ duplicates removed. So:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "text": {
         "type": "text",
@@ -233,8 +235,10 @@ are preserved.
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "text": { "type": "text", "store": true }
     }

docs/reference/mapping/types/version.asciidoc

@@ -86,8 +86,10 @@ Synthetic source always sorts `version` fields and removes duplicates. For examp
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "versions": { "type": "version" }
     }

docs/reference/mapping/types/wildcard.asciidoc

@@ -141,8 +141,10 @@ Synthetic source always sorts `wildcard` fields. For example:
 ----
 PUT idx
 {
+  "settings": {
+    "index.mapper.source.mode": "synthetic"
+  },
   "mappings": {
-    "_source": { "mode": "synthetic" },
     "properties": {
       "card": { "type": "wildcard" }
     }

modules/aggregations/src/yamlRestTest/resources/rest-api-spec/test/aggregations/top_hits.yml

@@ -356,9 +356,9 @@ synthetic _source:
       indices.create:
         index: test_synthetic
         body:
+          settings:
+            index.mapper.source.mode: synthetic
           mappings:
-            _source:
-              mode: synthetic
             properties:
               page:
                 type: keyword

modules/lang-painless/build.gradle

@@ -66,6 +66,10 @@ esplugin.bundleSpec.into("spi") {
     from(configurations.spi)
 }
 
+tasks.named("yamlRestCompatTestTransform").configure({ task ->
+  task.addAllowedWarning("The mode attribute for _source meta field mapper has been deprecated and will be removed in a future version")
+})
+
 /**********************************************
  *           Context API Generation           *
  **********************************************/

modules/lang-painless/src/yamlRestTest/resources/rest-api-spec/test/painless/50_script_doc_values.yml

@@ -179,10 +179,9 @@ setup:
         index: test_synthetic
         body:
           settings:
-            number_of_shards: 1
+            index.number_of_shards: 1
+            index.mapper.source.mode: synthetic
           mappings:
-            _source:
-              mode: synthetic
             properties:
               boolean:
                 type: boolean
@@ -5629,10 +5628,9 @@ version and sequence number synthetic _source:
         index: versiontest
         body:
           settings:
-            number_of_shards: 1
+            index.mapper.source.mode: synthetic
+            index.number_of_shards: 1
           mappings:
-            _source:
-              mode: synthetic
             properties:
               keyword:
                 type: keyword