ES|QL: Support STATS after FORK

x-pack/plugin/esql/qa/server/multi-clusters/src/javaRestTest/java/org/elasticsearch/xpack/esql/ccq/MultiClusterSpecIT.java

@@ -46,7 +46,7 @@
 import static org.elasticsearch.xpack.esql.CsvTestUtils.isEnabled;
 import static org.elasticsearch.xpack.esql.CsvTestsDataLoader.ENRICH_SOURCE_INDICES;
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.classpathResources;
-import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.FORK_V6;
+import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.FORK_V7;
 import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.INLINESTATS;
 import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.INLINESTATS_V2;
 import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.INLINESTATS_V7;
@@ -132,7 +132,7 @@ protected void shouldSkipTest(String testName) throws IOException {
         assumeFalse("LOOKUP JOIN not yet supported in CCS", testCase.requiredCapabilities.contains(JOIN_LOOKUP_V12.capabilityName()));
         // Unmapped fields require a coorect capability response from every cluster, which isn't currently implemented.
         assumeFalse("UNMAPPED FIELDS not yet supported in CCS", testCase.requiredCapabilities.contains(UNMAPPED_FIELDS.capabilityName()));
-        assumeFalse("FORK not yet supported in CCS", testCase.requiredCapabilities.contains(FORK_V6.capabilityName()));
+        assumeFalse("FORK not yet supported in CCS", testCase.requiredCapabilities.contains(FORK_V7.capabilityName()));
     }
 
     @Override

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

@@ -3,7 +3,7 @@
 //
 
 simpleFork
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | FORK ( WHERE emp_no == 10001 )
@@ -18,7 +18,7 @@ emp_no:integer | _fork:keyword
 ;
 
 forkWithWhereSortAndLimit
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | FORK ( WHERE hire_date < "1985-03-01T00:00:00Z" | SORT first_name | LIMIT 5 )
@@ -38,7 +38,7 @@ emp_no:integer | first_name:keyword | _fork:keyword
 ;
 
 fiveFork
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | FORK ( WHERE emp_no == 10005 )
@@ -59,7 +59,7 @@ fork5         | 10001
 ;
 
 forkWithWhereSortDescAndLimit
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | FORK ( WHERE hire_date < "1985-03-01T00:00:00Z" | SORT first_name DESC | LIMIT 2 )
@@ -76,7 +76,7 @@ fork2         | 10087          | Xinglin
 ;
 
 forkWithCommonPrefilter
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | WHERE emp_no > 10050
@@ -94,7 +94,7 @@ fork2         | 10100
 ;
 
 forkWithSemanticSearchAndScore
-required_capability: fork_v6
+required_capability: fork_v7
 required_capability: semantic_text_field_caps
 required_capability: metadata_score
 
@@ -114,7 +114,7 @@ fork2         | 6.093784261960139E18  | 2           | all we have to decide is w
 ;
 
 forkWithEvals
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | FORK (WHERE emp_no == 10048 OR emp_no == 10081 | EVAL x = "abc" | EVAL y = 1)
@@ -131,7 +131,7 @@ fork2         | 10087          | def       | null      | 2
 ;
 
 forkWithStats
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | FORK (WHERE emp_no == 10048 OR emp_no == 10081)
@@ -152,7 +152,7 @@ fork4         | null           | 100    | 10001     | null
 ;
 
 forkWithDissect
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | WHERE emp_no == 10048 OR emp_no == 10081
@@ -172,7 +172,7 @@ fork2         | 10081          | Rosen     | 10081     | null      | Zhongwei
 ;
 
 forkWithMixOfCommands
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | WHERE emp_no == 10048 OR emp_no == 10081
@@ -197,7 +197,7 @@ fork4         | 10081          | abc       | aaa       | null      | null
 ;
 
 forkWithFiltersOnConstantValues
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | EVAL z = 1
@@ -218,7 +218,7 @@ fork3         | null           | 100    | 10100     | 10001
 ;
 
 forkWithUnsupportedAttributes
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM heights
 | FORK (SORT description DESC | LIMIT 1 | EVAL x = length(description) )
@@ -232,7 +232,7 @@ Medium Height       | null                     | null      | fork2
 ;
 
 forkAfterLookupJoin
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | EVAL language_code = languages
@@ -253,7 +253,7 @@ fork3         | 10081          | 2                     | Klingon
 ;
 
 forkBeforeLookupJoin
-required_capability: fork_v6
+required_capability: fork_v7
 
 FROM employees
 | EVAL language_code = languages
@@ -272,3 +272,64 @@ fork2         | 10081          | 2                     | French
 fork2         | 10087          | 5                     | null
 fork3         | 10081          | 2                     | French
 ;
+
+
+forkBeforeStats
+required_capability: fork_v7
+
+FROM employees
+| WHERE emp_no == 10048 OR emp_no == 10081
+| FORK ( EVAL a = CONCAT(first_name, " ", emp_no::keyword, " ", last_name)
+        | DISSECT a "%{x} %{y} %{z}"
+        | EVAL y = y::keyword )
+       ( STATS x = COUNT(*)::keyword, y = MAX(emp_no)::keyword, z = MIN(emp_no)::keyword )
+       ( SORT emp_no ASC | LIMIT 2 | EVAL x = last_name )
+       ( EVAL x = "abc" | EVAL y = "aaa" )
+| STATS c = count(*), m = max(_fork)
+;
+
+c:long | m:keyword
+7      | fork4
+;
+
+forkBeforeStatsWithWhere
+required_capability: fork_v7
+
+FROM employees
+| WHERE emp_no == 10048 OR emp_no == 10081
+| FORK ( EVAL a = CONCAT(first_name, " ", emp_no::keyword, " ", last_name)
+        | DISSECT a "%{x} %{y} %{z}"
+        | EVAL y = y::keyword )
+       ( STATS x = COUNT(*)::keyword, y = MAX(emp_no)::keyword, z = MIN(emp_no)::keyword )
+       ( SORT emp_no ASC | LIMIT 2 | EVAL x = last_name )
+       ( EVAL x = "abc" | EVAL y = "aaa" )
+| STATS a = count(*) WHERE _fork == "fork1",
+        b = max(_fork)
+;
+
+a:long | b:keyword
+2      | fork4
+;
+
+forkBeforeStatsByWithWhere
+required_capability: fork_v7
+
+FROM employees
+| WHERE emp_no == 10048 OR emp_no == 10081
+| FORK ( EVAL a = CONCAT(first_name, " ", emp_no::keyword, " ", last_name)
+        | DISSECT a "%{x} %{y} %{z}"
+        | EVAL y = y::keyword )
+       ( STATS x = COUNT(*)::keyword, y = MAX(emp_no)::keyword, z = MIN(emp_no)::keyword )
+       ( SORT emp_no ASC | LIMIT 2 | EVAL x = last_name )
+       ( EVAL x = "abc" | EVAL y = "aaa" )
+| STATS a = count(*)  WHERE emp_no > 10000,
+        b = max(x) WHERE _fork == "fork1" BY _fork
+| SORT _fork
+;
+
+a:long | b:keyword | _fork:keyword
+2      | Zhongwei  | fork1
+0      | null      | fork2
+2      | null      | fork3
+2      | null      | fork4
+;

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/ForkIT.java

@@ -588,6 +588,39 @@ public void testWithStatsSimple() {
         }
     }
 
+    public void testWithStatsAfterFork() {
+        var query = """
+                FROM test
+                | FORK ( WHERE content:"fox" | EVAL a = 1)
+                       ( WHERE content:"cat" | EVAL b = 2 )
+                       ( WHERE content:"dog" | EVAL c = 3 )
+                | STATS c = count(*)
+            """;
+        try (var resp = run(query)) {
+            assertColumnNames(resp.columns(), List.of("c"));
+            assertColumnTypes(resp.columns(), List.of("long"));
+            Iterable<Iterable<Object>> expectedValues = List.of(List.of(7L));
+            assertValues(resp.values(), expectedValues);
+        }
+    }
+
+    public void testWithStatsWithWhereAfterFork() {
+        var query = """
+                FROM test
+                | FORK ( WHERE content:"fox" | EVAL a = 1)
+                       ( WHERE content:"cat" | EVAL b = 2 )
+                       ( WHERE content:"dog" | EVAL c = 3 )
+                | STATS c = count(*) WHERE _fork == "fork1"
+            """;
+        try (var resp = run(query)) {
+            assertColumnNames(resp.columns(), List.of("c"));
+            assertColumnTypes(resp.columns(), List.of("long"));
+
+            Iterable<Iterable<Object>> expectedValues = List.of(List.of(2L));
+            assertValues(resp.values(), expectedValues);
+        }
+    }
+
     public void testWithConditionOnForkField() {
         var query = """
                 FROM test

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

@@ -1035,7 +1035,7 @@ public enum Cap {
         /**
          * Support streaming of sub plan results
          */
-        FORK_V6(Build.current().isSnapshot()),
+        FORK_V7(Build.current().isSnapshot()),
 
         /**
          * Support for the {@code leading_zeros} named parameter.

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

@@ -318,7 +318,7 @@ public final void test() throws Throwable {
             );
             assumeFalse(
                 "CSV tests cannot currently handle FORK",
-                testCase.requiredCapabilities.contains(EsqlCapabilities.Cap.FORK_V6.capabilityName())
+                testCase.requiredCapabilities.contains(EsqlCapabilities.Cap.FORK_V7.capabilityName())
             );
             assumeFalse(
                 "CSV tests cannot currently handle multi_match function that depends on Lucene",