Handle subqueries

Author: felixbarny

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

@@ -301,7 +301,7 @@ static CsvSpecReader.CsvTestCase convertToRemoteIndices(CsvSpecReader.CsvTestCas
         String query = testCase.query;
         // If true, we're using *:index, otherwise we're using *:index,index
         boolean onlyRemotes = canUseRemoteIndicesOnly() && randomBoolean();
-        testCase.query = EsqlTestUtils.addRemotes(testCase.query, LOOKUP_INDICES, onlyRemotes);
+        testCase.query = EsqlTestUtils.addRemoteIndices(testCase.query, LOOKUP_INDICES, onlyRemotes);
 
         int offset = testCase.query.length() - query.length();
         if (offset != 0) {

x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/EsqlTestUtils.java

@@ -1284,9 +1284,10 @@ private static PhysicalPlan ignoreIdsInPhysicalPlan(PhysicalPlan plan) {
         });
     }
 
-    public static String addRemotes(String query, Set<String> lookupIndices, boolean onlyRemotes) {
+    public static String addRemoteIndices(String query, Set<String> lookupIndices, boolean onlyRemotes) {
         String[] commands = query.split("\\|");
-        String first = commands[0].trim();
+        // remove subqueries
+        String first = commands[0].split(",\\s+\\(")[0].trim();
 
         // Split "SET a=b; FROM x" into "SET a=b" and "FROM x"
         int lastSetDelimiterPosition = first.lastIndexOf(';');

x-pack/plugin/esql/qa/testFixtures/src/test/java/org/elasticsearch/xpack/esql/EsqlTestUtilsTests.java

@@ -17,54 +17,75 @@ public class EsqlTestUtilsTests extends ESTestCase {
 
     public void testPromQL() {
         assertThat(
-            EsqlTestUtils.addRemotes("PROMQL foo, bar step 1m (avg(baz))", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("PROMQL foo, bar step 1m (avg(baz))", Set.of(), false),
             equalTo("PROMQL *:foo,foo,*:bar,bar step 1m (avg(baz))")
         );
         assertThat(
-            EsqlTestUtils.addRemotes("PROMQL \"foo\", \"bar\" step 1m (avg(baz))", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("PROMQL \"foo\", \"bar\" step 1m (avg(baz))", Set.of(), false),
             equalTo("PROMQL *:foo,foo,*:bar,bar step 1m (avg(baz))")
         );
     }
 
     public void testPromQLDefaultIndex() {
         assertThat(
-            EsqlTestUtils.addRemotes("PROMQL step 1m (avg(baz))", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("PROMQL step 1m (avg(baz))", Set.of(), false),
             equalTo("PROMQL *:*,* step 1m (avg(baz))")
         );
     }
 
     public void testSet() {
         assertThat(
-            EsqlTestUtils.addRemotes("SET a=b; FROM foo | SORT bar", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("SET a=b; FROM foo | SORT bar", Set.of(), false),
             equalTo("SET a=b; FROM *:foo,foo | SORT bar")
         );
     }
 
     public void testMetadata() {
         assertThat(
-            EsqlTestUtils.addRemotes("FROM foo METADATA _source | SORT bar", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("FROM foo METADATA _source | SORT bar", Set.of(), false),
             equalTo("FROM *:foo,foo METADATA _source | SORT bar")
         );
     }
 
     public void testTS() {
         assertThat(
-            EsqlTestUtils.addRemotes("TS foo, \"bar\",baz | SORT bar", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("TS foo, \"bar\",baz | SORT bar", Set.of(), false),
             equalTo("TS *:foo,foo,*:bar,bar,*:baz,baz | SORT bar")
         );
     }
 
     public void testIndexPatternWildcard() {
         assertThat(
-            EsqlTestUtils.addRemotes("TS fo* | SORT bar", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("TS fo* | SORT bar", Set.of(), false),
             equalTo("TS *:fo*,fo* | SORT bar")
         );
     }
 
     public void testDuplicateIndex() {
         assertThat(
-            EsqlTestUtils.addRemotes("TS foo,bar,foo | SORT bar", Set.of(), false),
+            EsqlTestUtils.addRemoteIndices("TS foo,bar,foo | SORT bar", Set.of(), false),
             equalTo("TS *:foo,foo,*:bar,bar,*:foo,foo | SORT bar")
         );
     }
+
+    public void testSubquery() {
+        assertThat(
+            EsqlTestUtils.addRemoteIndices("""
+                FROM employees, (FROM employees_incompatible
+                                 | ENRICH languages_policy on languages with language_name )
+                           metadata _index
+                | EVAL emp_no = emp_no::long
+                | WHERE emp_no >= 10091 AND emp_no < 10094
+                | SORT _index, emp_no
+                | KEEP _index,  emp_no, languages, language_name""", Set.of(), false),
+            equalTo("""
+                FROM *:employees,employees, (FROM employees_incompatible
+                                 | ENRICH languages_policy on languages with language_name )
+                           metadata _index
+                | EVAL emp_no = emp_no::long
+                | WHERE emp_no >= 10091 AND emp_no < 10094
+                | SORT _index, emp_no
+                | KEEP _index,  emp_no, languages, language_name""")
+        );
+    }
 }