Field capabilities - make keyword a family of field types (#58315) (#58483)

Introduces a new method on `MappedFieldType` to return a family type name which defaults to the field type.
Changes `wildcard` and `constant_keyword` field types to return `keyword` for field capabilities.

Relates to #53175

Author: markharwood

docs/reference/search/field-caps.asciidoc

@@ -67,6 +67,13 @@ query rewrites to `match_none` on every shard.
 ==== {api-response-body-title}
 
 
+The types used in the response describe _families_ of field types.
+Normally a family type is the same as the field type declared in the mapping,
+but to simplify matters certain field types that behave identically are
+described using a family type. For example, `keyword`, `constant_keyword` and `wildcard`
+field types are all described as the `keyword` family type.
+
+
 
 `searchable`::
   Whether this field is indexed for search on all indices.
@@ -75,8 +82,8 @@ query rewrites to `match_none` on every shard.
   Whether this field can be aggregated on all indices.
 
 `indices`::
-  The list of indices where this field has the same type, or null if all indices
-  have the same type for the field.
+  The list of indices where this field has the same family type, or null if all indices
+  have the same family type for the field.
 
 `non_searchable_indices`::
   The list of indices where this field is not searchable, or null if all indices

server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesIndexAction.java

@@ -124,7 +124,7 @@ private FieldCapabilitiesIndexResponse shardOperation(final FieldCapabilitiesInd
             if (ft != null) {
                 if (indicesService.isMetadataField(mapperService.getIndexSettings().getIndexVersionCreated(), field)
                     || fieldPredicate.test(ft.name())) {
-                    IndexFieldCapabilities fieldCap = new IndexFieldCapabilities(field, ft.typeName(),
+                    IndexFieldCapabilities fieldCap = new IndexFieldCapabilities(field, ft.familyTypeName(),
                         ft.isSearchable(), ft.isAggregatable(), ft.meta());
                     responseMap.put(field, fieldCap);
                 } else {

server/src/main/java/org/elasticsearch/index/mapper/MappedFieldType.java

@@ -135,6 +135,11 @@ public int hashCode() {
 
     /** Returns the name of this type, as would be specified in mapping properties */
     public abstract String typeName();
+    
+    /** Returns the field family type, as used in field capabilities */
+    public String familyTypeName() {
+        return typeName();
+    }
 
     public String name() {
         return name;

x-pack/plugin/mapper-constant-keyword/src/main/java/org/elasticsearch/xpack/constantkeyword/mapper/ConstantKeywordFieldMapper.java

@@ -30,6 +30,7 @@
 import org.elasticsearch.index.fielddata.plain.ConstantIndexFieldData;
 import org.elasticsearch.index.mapper.ConstantFieldType;
 import org.elasticsearch.index.mapper.FieldMapper;
+import org.elasticsearch.index.mapper.KeywordFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.Mapper;
 import org.elasticsearch.index.mapper.MapperParsingException;
@@ -151,6 +152,11 @@ public String value() {
         public String typeName() {
             return CONTENT_TYPE;
         }
+        
+        @Override
+        public String familyTypeName() {
+            return KeywordFieldMapper.CONTENT_TYPE;
+        }        
 
         @Override
         public IndexFieldData.Builder fielddataBuilder(String fullyQualifiedIndexName) {

x-pack/plugin/sql/qa/server/src/main/java/org/elasticsearch/xpack/sql/qa/FieldExtractorTestCase.java

@@ -128,7 +128,7 @@ public void testConstantKeywordField() throws IOException {
         Map<String, Object> expected = new HashMap<>();
         expected.put(
             "columns",
-            Arrays.asList(columnInfo("plain", "constant_keyword_field", "constant_keyword", JDBCType.VARCHAR, Integer.MAX_VALUE))
+            Arrays.asList(columnInfo("plain", "constant_keyword_field", "keyword", JDBCType.VARCHAR, Integer.MAX_VALUE))
         );
         expected.put("rows", singletonList(singletonList(value)));
         assertResponse(expected, runSql("SELECT constant_keyword_field FROM test"));

x-pack/plugin/sql/qa/server/src/main/resources/alias.csv-spec

@@ -41,7 +41,7 @@ emp_no              |INTEGER        |integer
 extra               |STRUCT         |object
 extra.info          |STRUCT         |object
 extra.info.gender   |VARCHAR        |keyword
-extra_gender        |VARCHAR        |constant_keyword
+extra_gender        |VARCHAR        |keyword
 extra_no            |INTEGER        |integer
 first_name          |VARCHAR        |text
 first_name.keyword  |VARCHAR        |keyword
@@ -50,7 +50,7 @@ hire_date           |TIMESTAMP      |datetime
 languages           |TINYINT        |byte
 last_name           |VARCHAR        |text
 last_name.keyword   |VARCHAR        |keyword
-null_constant       |VARCHAR        |constant_keyword
+null_constant       |VARCHAR        |keyword
 salary              |INTEGER        |integer
 ;
 
@@ -70,7 +70,7 @@ emp_no              |INTEGER        |integer
 extra               |STRUCT         |object
 extra.info          |STRUCT         |object
 extra.info.gender   |VARCHAR        |keyword
-extra_gender        |VARCHAR        |constant_keyword
+extra_gender        |VARCHAR        |keyword
 extra_no            |INTEGER        |integer
 first_name          |VARCHAR        |text
 first_name.keyword  |VARCHAR        |keyword
@@ -79,7 +79,7 @@ hire_date           |TIMESTAMP      |datetime
 languages           |TINYINT        |byte
 last_name           |VARCHAR        |text
 last_name.keyword   |VARCHAR        |keyword
-null_constant       |VARCHAR        |constant_keyword
+null_constant       |VARCHAR        |keyword
 salary              |INTEGER        |integer
 ;
 

x-pack/plugin/sql/qa/server/src/main/resources/command.csv-spec

@@ -281,7 +281,7 @@ emp_no              |INTEGER        |integer
 extra               |STRUCT         |object
 extra.info          |STRUCT         |object
 extra.info.gender   |VARCHAR        |keyword
-extra_gender        |VARCHAR        |constant_keyword
+extra_gender        |VARCHAR        |keyword
 extra_no            |INTEGER        |integer
 first_name          |VARCHAR        |text
 first_name.keyword  |VARCHAR        |keyword
@@ -290,7 +290,7 @@ hire_date           |TIMESTAMP      |datetime
 languages           |TINYINT        |byte
 last_name           |VARCHAR        |text
 last_name.keyword   |VARCHAR        |keyword
-null_constant       |VARCHAR        |constant_keyword
+null_constant       |VARCHAR        |keyword
 salary              |INTEGER        |integer
 ;
 
@@ -310,7 +310,7 @@ emp_no              |INTEGER        |integer
 extra               |STRUCT         |object
 extra.info          |STRUCT         |object
 extra.info.gender   |VARCHAR        |keyword
-extra_gender        |VARCHAR        |constant_keyword
+extra_gender        |VARCHAR        |keyword
 extra_no            |INTEGER        |integer
 first_name          |VARCHAR        |text
 first_name.keyword  |VARCHAR        |keyword
@@ -319,7 +319,7 @@ hire_date           |TIMESTAMP      |datetime
 languages           |TINYINT        |byte
 last_name           |VARCHAR        |text
 last_name.keyword   |VARCHAR        |keyword
-null_constant       |VARCHAR        |constant_keyword
+null_constant       |VARCHAR        |keyword
 salary              |INTEGER        |integer
 ;