Synthetic source: load text from stored fields (#87480)

Adds support for loading `text` and `keyword` fields that have
`store: true`. We could likely load *any* stored fields, but I
wanted to blaze the trail using something fairly useful.

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/ScaledFloatFieldMapper.java

@@ -34,6 +34,7 @@
 import org.elasticsearch.index.mapper.MapperBuilderContext;
 import org.elasticsearch.index.mapper.NumberFieldMapper;
 import org.elasticsearch.index.mapper.SimpleMappedFieldType;
+import org.elasticsearch.index.mapper.SortedNumericDocValuesSyntheticFieldLoader;
 import org.elasticsearch.index.mapper.SourceLoader;
 import org.elasticsearch.index.mapper.SourceValueFetcher;
 import org.elasticsearch.index.mapper.TextSearchInfo;
@@ -705,7 +706,7 @@ public SourceLoader.SyntheticFieldLoader syntheticFieldLoader() {
                 "field [" + name() + "] of type [" + typeName() + "] doesn't support synthetic source because it declares copy_to"
             );
         }
-        return new NumberFieldMapper.NumericSyntheticFieldLoader(name(), simpleName()) {
+        return new SortedNumericDocValuesSyntheticFieldLoader(name(), simpleName()) {
             @Override
             protected void writeValue(XContentBuilder b, long value) throws IOException {
                 b.value(decodeForSyntheticSource(value, scalingFactor));

modules/parent-join/src/yamlRestTest/resources/rest-api-spec/test/60_synthetic_source.yml

@@ -10,7 +10,7 @@ unsupported:
         body:
           mappings:
             _source:
-              synthetic: true
+              mode: synthetic
             properties:
               join_field:
                 type: join

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/get/100_synthetic_source.yml

@@ -167,3 +167,79 @@ force_synthetic_source_bad_mapping:
         index: test
         id: 1
         force_synthetic_source: true
+
+---
+stored text:
+  - skip:
+      version: " - 8.4.99"
+      reason: introduced in 8.5.0
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            _source:
+              mode: synthetic
+            properties:
+              text:
+                type: text
+                store: true
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        refresh: true
+        body:
+          text: the quick brown fox
+
+  - do:
+      get:
+        index: test
+        id:    1
+  - match: {_index: "test"}
+  - match: {_id: "1"}
+  - match: {_version: 1}
+  - match: {found: true}
+  - match:
+      _source:
+        text: the quick brown fox
+
+---
+stored keyword:
+  - skip:
+      version: " - 8.4.99"
+      reason: introduced in 8.5.0
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            _source:
+              mode: synthetic
+            properties:
+              kwd:
+                type: keyword
+                store: true
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        refresh: true
+        body:
+          kwd: the quick brown fox
+
+  - do:
+      get:
+        index: test
+        id:    1
+  - match: {_index: "test"}
+  - match: {_id: "1"}
+  - match: {_version: 1}
+  - match: {found: true}
+  - match:
+      _source:
+        kwd: the quick brown fox

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/mget/90_synthetic_source.yml

@@ -46,6 +46,55 @@ keyword:
       docs.1._source:
         kwd: bar
 
+---
+stored text:
+  - skip:
+      version: " - 8.4.99"
+      reason: introduced in 8.5.0
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            _source:
+              mode: synthetic
+            properties:
+              text:
+                type: text
+                store: true
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:
+          text: the quick brown fox
+
+  - do:
+      index:
+        index:   test
+        id:      2
+        body:
+          text: jumped over the lazy dog
+
+  - do:
+      mget:
+        index: test
+        body:
+          ids:    [1, 2]
+  - match: {docs.0._index: "test"}
+  - match: {docs.0._id: "1"}
+  - match:
+      docs.0._source:
+        text: the quick brown fox
+
+  - match: {docs.1._index: "test"}
+  - match: {docs.1._id: "2"}
+  - match:
+      docs.1._source:
+        text: jumped over the lazy dog
+
 ---
 force_synthetic_source_ok:
   - skip:
@@ -60,22 +109,25 @@ force_synthetic_source_ok:
             _source:
               mode: stored
             properties:
-              kwd:
-                type: keyword
+              obj:
+                properties:
+                  kwd:
+                    type: keyword
 
   - do:
       index:
         index:   test
         id:      1
         body:
-          kwd: foo
+          obj.kwd: foo
 
   - do:
       index:
         index:   test
         id:      2
         body:
-          kwd: bar
+          obj:
+            kwd: bar
 
   # When _source is used in the fetch the original _source is perfect
   - do:
@@ -85,10 +137,11 @@ force_synthetic_source_ok:
           ids: [1, 2]
   - match:
       docs.0._source:
-        kwd: foo
+        obj.kwd: foo
   - match:
       docs.1._source:
-        kwd: bar
+        obj:
+          kwd: bar
 
   # When we force synthetic source dots in field names get turned into objects
   - do:
@@ -99,16 +152,18 @@ force_synthetic_source_ok:
           ids: [ 1, 2 ]
   - match:
       docs.0._source:
-        kwd: foo
+        obj:
+          kwd: foo
   - match:
       docs.1._source:
-        kwd: bar
+        obj:
+          kwd: bar
 
 ---
 force_synthetic_source_bad_mapping:
   - skip:
-      version: " - 8.3.99"
-      reason: introduced in 8.4.0
+      version: " - 8.4.99"
+      reason: message changed in 8.5
 
   - do:
       indices.create:
@@ -157,5 +212,5 @@ force_synthetic_source_bad_mapping:
         force_synthetic_source: true
         body:
           ids: [ 1, 2 ]
-  - match: {docs.0.error.reason: "field [text] of type [text] doesn't support synthetic source unless it has a sub-field of type [keyword] with doc values enabled and without ignore_above or a normalizer"}
-  - match: {docs.1.error.reason: "field [text] of type [text] doesn't support synthetic source unless it has a sub-field of type [keyword] with doc values enabled and without ignore_above or a normalizer"}
+  - match: {docs.0.error.reason: "field [text] of type [text] doesn't support synthetic source unless it is stored or has a sub-field of type [keyword] with doc values or stored and without ignore_above or a normalizer"}
+  - match: {docs.1.error.reason: "field [text] of type [text] doesn't support synthetic source unless it is stored or has a sub-field of type [keyword] with doc values or stored and without ignore_above or a normalizer"}

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search/400_synthetic_source.yml

@@ -33,6 +33,123 @@ keyword:
       hits.hits.0._source:
         kwd: foo
 
+---
+stored text:
+  - skip:
+      version: " - 8.4.99"
+      reason: introduced in 8.5.0
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            _source:
+              mode: synthetic
+            properties:
+              text:
+                type: text
+                store: true
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        refresh: true
+        body:
+          text: the quick brown fox
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            ids:
+              values: [1]
+  - match:
+      hits.hits.0._source:
+        text: the quick brown fox
+
+---
+stored keyword:
+  - skip:
+      version: " - 8.4.99"
+      reason: introduced in 8.5.0
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            _source:
+              mode: synthetic
+            properties:
+              kwd:
+                type: keyword
+                store: true
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        refresh: true
+        body:
+          kwd: the quick brown fox
+
+  - do:
+      search:
+        index: test
+        body:
+          query:
+            ids:
+              values: [1]
+  - match:
+      hits.hits.0._source:
+        kwd: the quick brown fox
+
+---
+stored keyword without sibling fields:
+  - skip:
+      version: " - 8.4.99"
+      reason: introduced in 8.5.0
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          mappings:
+            _source:
+              mode: synthetic
+            properties:
+              kwd:
+                type: keyword
+                store: true
+
+  - do:
+      bulk:
+        refresh: true
+        index: test
+        body:
+          - '{"index": {}}'
+          - '{"kwd": "the quick brown fox", "s": 1, "n": 1}'
+          - '{"index": {}}'
+          - '{"kwd": "jumped over the lazy dog", "s": 2}'
+
+  - do:
+      search:
+        index: test
+        body:
+          sort: s
+  - match:
+      hits.hits.0._source:
+        kwd: the quick brown fox
+        s: 1
+        n: 1
+  - match:
+      hits.hits.1._source:
+        kwd: jumped over the lazy dog
+        s: 2
+
 ---
 force_synthetic_source_ok:
   - skip: