Support multi-index LOOKUP JOIN and various bug fixes (#118429)

While working on supporting multi-index LOOKUP JOIN; various bugs were
fixed:

* Previously we just used '*' for lookup-join indices, because the fieldnames were sometimes not being correctly determined. The problem was with KEEP referencing fields from the right that had previously been defined on the left as aliases, including using the ROW command. We normally don't want to ask for aliases, but if they could be shadowed by a lookup join, we need to keep them.
* With both single and multi-index LOOKUP JOIN we need to mark each index as potentially wildcard fields, if the KEEP commands occur before the LOOKUP JOIN.

Author: craigtaverner

x-pack/plugin/esql/qa/server/mixed-cluster/src/javaRestTest/java/org/elasticsearch/xpack/esql/qa/mixed/MixedClusterEsqlSpecIT.java

@@ -21,7 +21,7 @@
 import java.util.List;
 
 import static org.elasticsearch.xpack.esql.CsvTestUtils.isEnabled;
-import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.JOIN_LOOKUP_V5;
+import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.JOIN_LOOKUP_V6;
 import static org.elasticsearch.xpack.esql.qa.rest.EsqlSpecTestCase.Mode.ASYNC;
 
 public class MixedClusterEsqlSpecIT extends EsqlSpecTestCase {
@@ -96,7 +96,7 @@ protected boolean supportsInferenceTestService() {
 
     @Override
     protected boolean supportsIndexModeLookup() throws IOException {
-        return hasCapabilities(List.of(JOIN_LOOKUP_V5.capabilityName()));
+        return hasCapabilities(List.of(JOIN_LOOKUP_V6.capabilityName()));
     }
 
     @Override

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

@@ -48,7 +48,7 @@
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.classpathResources;
 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.JOIN_LOOKUP_V5;
+import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.JOIN_LOOKUP_V6;
 import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.JOIN_PLANNING_V1;
 import static org.elasticsearch.xpack.esql.action.EsqlCapabilities.Cap.METADATA_FIELDS_REMOTE_TEST;
 import static org.elasticsearch.xpack.esql.qa.rest.EsqlSpecTestCase.Mode.SYNC;
@@ -124,7 +124,7 @@ protected void shouldSkipTest(String testName) throws IOException {
         assumeFalse("INLINESTATS not yet supported in CCS", testCase.requiredCapabilities.contains(INLINESTATS.capabilityName()));
         assumeFalse("INLINESTATS not yet supported in CCS", testCase.requiredCapabilities.contains(INLINESTATS_V2.capabilityName()));
         assumeFalse("INLINESTATS not yet supported in CCS", testCase.requiredCapabilities.contains(JOIN_PLANNING_V1.capabilityName()));
-        assumeFalse("LOOKUP JOIN not yet supported in CCS", testCase.requiredCapabilities.contains(JOIN_LOOKUP_V5.capabilityName()));
+        assumeFalse("LOOKUP JOIN not yet supported in CCS", testCase.requiredCapabilities.contains(JOIN_LOOKUP_V6.capabilityName()));
     }
 
     private TestFeatureService remoteFeaturesService() throws IOException {
@@ -283,8 +283,8 @@ protected boolean supportsInferenceTestService() {
 
     @Override
     protected boolean supportsIndexModeLookup() throws IOException {
-        // CCS does not yet support JOIN_LOOKUP_V5 and clusters falsely report they have this capability
-        // return hasCapabilities(List.of(JOIN_LOOKUP_V5.capabilityName()));
+        // CCS does not yet support JOIN_LOOKUP_V6 and clusters falsely report they have this capability
+        // return hasCapabilities(List.of(JOIN_LOOKUP_V6.capabilityName()));
         return false;
     }
 }

x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/RequestIndexFilteringTestCase.java

@@ -14,6 +14,7 @@
 import org.elasticsearch.test.rest.ESRestTestCase;
 import org.elasticsearch.xcontent.XContentType;
 import org.elasticsearch.xpack.esql.AssertWarnings;
+import org.elasticsearch.xpack.esql.action.EsqlCapabilities;
 import org.junit.After;
 import org.junit.Assert;
 
@@ -219,6 +220,16 @@ public void testIndicesDontExist() throws IOException {
         assertEquals(404, e.getResponse().getStatusLine().getStatusCode());
         assertThat(e.getMessage(), containsString("index_not_found_exception"));
         assertThat(e.getMessage(), containsString("no such index [foo]"));
+
+        if (EsqlCapabilities.Cap.JOIN_LOOKUP_V6.isEnabled()) {
+            e = expectThrows(
+                ResponseException.class,
+                () -> runEsql(timestampFilter("gte", "2020-01-01").query("FROM test1 | LOOKUP JOIN foo ON id1"))
+            );
+            assertEquals(400, e.getResponse().getStatusLine().getStatusCode());
+            assertThat(e.getMessage(), containsString("verification_exception"));
+            assertThat(e.getMessage(), containsString("Unknown index [foo]"));
+        }
     }
 
     private static RestEsqlTestCase.RequestObjectBuilder timestampFilter(String op, String date) throws IOException {