ES|QL: support dot and parameters in FUSE GROUP BY

docs/changelog/135901.yaml

@@ -0,0 +1,5 @@
+pr: 135901
+summary: Support dot for attribute names in FUSE GROUP BY
+area: ES|QL
+type: bug
+issues: []

x-pack/plugin/esql/qa/testFixtures/src/main/resources/fuse.csv-spec

@@ -281,6 +281,33 @@ _score:double | new_fork:keyword  | _id:keyword
 0.01587       | fork1             | 26
 ;
 
+fuseWithRrfAndDiscriminatorColumnWithDots
+required_capability: fork_v9
+required_capability: fuse_v6
+required_capability: semantic_text_field_caps
+required_capability: metadata_score
+required_capability: dots_in_fuse
+
+FROM books METADATA _id, _index, _score
+| FORK ( WHERE title:"Tolkien" | SORT _score, _id DESC | LIMIT 3)
+       ( WHERE author:"Tolkien" | SORT _score, _id DESC | LIMIT 3)
+| EVAL new.fork = _fork
+| DROP _fork
+| FUSE rrf GROUP BY new.fork
+| SORT _score DESC, _id, _index
+| EVAL new.fork = mv_sort(new.fork)
+| EVAL _score = round(_score, 5)
+| KEEP _score, new.fork, _id
+;
+
+_score:double | new.fork:keyword  | _id:keyword
+0.03279       | [fork1, fork2]    | 4
+0.01613       | fork1             | 56
+0.01613       | fork2             | 60
+0.01587       | fork2             | 1
+0.01587       | fork1             | 26
+;
+
 fuseWithRrfAndKeyColumns
 required_capability: fork_v9
 required_capability: fuse_v6

x-pack/plugin/esql/src/main/antlr/lexer/Fuse.g4

@@ -20,6 +20,7 @@ KEY : 'key';
 
 FUSE_WITH: WITH -> type(WITH), popMode, pushMode(EXPRESSION_MODE);
 FUSE_COMMA: COMMA -> type(COMMA);
+FUSE_DOT: DOT -> type(DOT);
 FUSE_BY: BY -> type(BY);
 FUSE_QUOTED_IDENTIFIER: QUOTED_IDENTIFIER -> type(QUOTED_IDENTIFIER);
 FUSE_UNQUOTED_IDENTIFIER: UNQUOTED_IDENTIFIER -> type(UNQUOTED_IDENTIFIER);

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -1593,7 +1593,12 @@ public enum Cap {
          * Fix management of plans with no columns
          * https://github.com/elastic/elasticsearch/issues/120272
          */
-        FIX_NO_COLUMNS;
+        FIX_NO_COLUMNS,
+
+        /**
+         * Support for dots in FUSE attributes
+         */
+        DOTS_IN_FUSE;
 
         private final boolean enabled;
 

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/parser/StatementParserTests.java

@@ -4307,6 +4307,26 @@ public void testValidFuse() {
         assertThat(fuse.fuseType(), equalTo(Fuse.FuseType.RRF));
         options = fuse.options();
         assertThat(options.get("rank_constant"), equalTo(Literal.integer(null, 15)));
+
+        plan = statement("""
+                FROM foo* METADATA _id, _index, _score
+                | EVAL a.b = my_group
+                | FORK ( WHERE a:"baz" )
+                       ( WHERE b:"bar" )
+                | FUSE GROUP BY a.b KEY BY my_key1,my_key2 SCORE BY my_score WITH {"rank_constant": 15 }
+            """);
+
+        fuse = as(plan, Fuse.class);
+        assertThat(fuse.keys().size(), equalTo(2));
+        assertThat(fuse.keys().get(0), instanceOf(UnresolvedAttribute.class));
+        assertThat(fuse.keys().get(0).name(), equalTo("my_key1"));
+        assertThat(fuse.keys().get(1), instanceOf(UnresolvedAttribute.class));
+        assertThat(fuse.keys().get(1).name(), equalTo("my_key2"));
+        assertThat(fuse.discriminator().name(), equalTo("a.b"));
+        assertThat(fuse.score().name(), equalTo("my_score"));
+        assertThat(fuse.fuseType(), equalTo(Fuse.FuseType.RRF));
+        options = fuse.options();
+        assertThat(options.get("rank_constant"), equalTo(Literal.integer(null, 15)));
     }
 
     public void testInvalidFuse() {