Disallow CCS with lookup join

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/parser/LogicalPlanBuilder.java

@@ -11,10 +11,12 @@
 import org.antlr.v4.runtime.Token;
 import org.antlr.v4.runtime.tree.ParseTree;
 import org.elasticsearch.Build;
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.core.Tuple;
 import org.elasticsearch.dissect.DissectException;
 import org.elasticsearch.dissect.DissectParser;
 import org.elasticsearch.index.IndexMode;
+import org.elasticsearch.transport.RemoteClusterAware;
 import org.elasticsearch.xpack.esql.VerificationException;
 import org.elasticsearch.xpack.esql.common.Failure;
 import org.elasticsearch.xpack.esql.core.expression.Alias;
@@ -527,6 +529,13 @@ public PlanFactory visitJoinCommand(EsqlBaseParser.JoinCommandContext ctx) {
         if (rightPattern.contains(WILDCARD)) {
             throw new ParsingException(source(target), "invalid index pattern [{}], * is not allowed in LOOKUP JOIN", rightPattern);
         }
+        if (RemoteClusterAware.isRemoteIndexName(rightPattern)) {
+            throw new ParsingException(
+                source(target),
+                "invalid index pattern [{}], remote clusters are not supported in LOOKUP JOIN",
+                rightPattern
+            );
+        }
 
         UnresolvedRelation right = new UnresolvedRelation(
             source(target),
@@ -557,6 +566,20 @@ public PlanFactory visitJoinCommand(EsqlBaseParser.JoinCommandContext ctx) {
             throw new ParsingException(source, "JOIN ON clause only supports one field at the moment, found [{}]", matchFieldsCount);
         }
 
-        return p -> new LookupJoin(source, p, right, joinFields);
+        return p -> {
+            p.forEachUp(UnresolvedRelation.class, r -> {
+                for (var leftPattern : Strings.splitStringByCommaToArray(r.table().index())) {
+                    if (RemoteClusterAware.isRemoteIndexName(leftPattern)) {
+                        throw new ParsingException(
+                            source(target),
+                            "invalid index pattern [{}], remote clusters are not supported in LOOKUP JOIN",
+                            r.table().index()
+                        );
+                    }
+                }
+            });
+
+            return new LookupJoin(source, p, right, joinFields);
+        };
     }
 }

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

@@ -78,6 +78,7 @@
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.paramAsIdentifier;
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.paramAsPattern;
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.referenceAttribute;
+import static org.elasticsearch.xpack.esql.IdentifierGenerator.Features.CROSS_CLUSTER;
 import static org.elasticsearch.xpack.esql.IdentifierGenerator.Features.WILDCARD_PATTERN;
 import static org.elasticsearch.xpack.esql.IdentifierGenerator.randomIndexPattern;
 import static org.elasticsearch.xpack.esql.IdentifierGenerator.randomIndexPatterns;
@@ -307,18 +308,18 @@ public void testStatsWithoutGroups() {
         );
     }
 
-    public void testStatsWithoutAggs() throws Exception {
+    public void testStatsWithoutAggs() {
         assertEquals(
             new Aggregate(EMPTY, PROCESSING_CMD_INPUT, Aggregate.AggregateType.STANDARD, List.of(attribute("a")), List.of(attribute("a"))),
             processingCommand("stats by a")
         );
     }
 
-    public void testStatsWithoutAggsOrGroup() throws Exception {
+    public void testStatsWithoutAggsOrGroup() {
         expectError("from text | stats", "At least one aggregation or grouping expression required in [stats]");
     }
 
-    public void testAggsWithGroupKeyAsAgg() throws Exception {
+    public void testAggsWithGroupKeyAsAgg() {
         var queries = new String[] { """
             row a = 1, b = 2
             | stats a by a
@@ -339,7 +340,7 @@ public void testAggsWithGroupKeyAsAgg() throws Exception {
         }
     }
 
-    public void testStatsWithGroupKeyAndAggFilter() throws Exception {
+    public void testStatsWithGroupKeyAndAggFilter() {
         var a = attribute("a");
         var f = new UnresolvedFunction(EMPTY, "min", DEFAULT, List.of(a));
         var filter = new Alias(EMPTY, "min(a) where a > 1", new FilteredExpression(EMPTY, f, new GreaterThan(EMPTY, a, integer(1))));
@@ -349,7 +350,7 @@ public void testStatsWithGroupKeyAndAggFilter() throws Exception {
         );
     }
 
-    public void testStatsWithGroupKeyAndMixedAggAndFilter() throws Exception {
+    public void testStatsWithGroupKeyAndMixedAggAndFilter() {
         var a = attribute("a");
         var min = new UnresolvedFunction(EMPTY, "min", DEFAULT, List.of(a));
         var max = new UnresolvedFunction(EMPTY, "max", DEFAULT, List.of(a));
@@ -384,7 +385,7 @@ public void testStatsWithGroupKeyAndMixedAggAndFilter() throws Exception {
         );
     }
 
-    public void testStatsWithoutGroupKeyMixedAggAndFilter() throws Exception {
+    public void testStatsWithoutGroupKeyMixedAggAndFilter() {
         var a = attribute("a");
         var f = new UnresolvedFunction(EMPTY, "min", DEFAULT, List.of(a));
         var filter = new Alias(EMPTY, "min(a) where a > 1", new FilteredExpression(EMPTY, f, new GreaterThan(EMPTY, a, integer(1))));
@@ -2067,41 +2068,41 @@ private void assertStringAsLookupIndexPattern(String string, String statement) {
         assertThat(tableName.fold(FoldContext.small()), equalTo(string));
     }
 
-    public void testIdPatternUnquoted() throws Exception {
+    public void testIdPatternUnquoted() {
         var string = "regularString";
         assertThat(breakIntoFragments(string), contains(string));
     }
 
-    public void testIdPatternQuoted() throws Exception {
+    public void testIdPatternQuoted() {
         var string = "`escaped string`";
         assertThat(breakIntoFragments(string), contains(string));
     }
 
-    public void testIdPatternQuotedWithDoubleBackticks() throws Exception {
+    public void testIdPatternQuotedWithDoubleBackticks() {
         var string = "`escaped``string`";
         assertThat(breakIntoFragments(string), contains(string));
     }
 
-    public void testIdPatternUnquotedAndQuoted() throws Exception {
+    public void testIdPatternUnquotedAndQuoted() {
         var string = "this`is`a`mix`of`ids`";
         assertThat(breakIntoFragments(string), contains("this", "`is`", "a", "`mix`", "of", "`ids`"));
     }
 
-    public void testIdPatternQuotedTraling() throws Exception {
+    public void testIdPatternQuotedTraling() {
         var string = "`foo`*";
         assertThat(breakIntoFragments(string), contains("`foo`", "*"));
     }
 
-    public void testIdPatternWithDoubleQuotedStrings() throws Exception {
+    public void testIdPatternWithDoubleQuotedStrings() {
         var string = "`this``is`a`quoted `` string``with`backticks";
         assertThat(breakIntoFragments(string), contains("`this``is`", "a", "`quoted `` string``with`", "backticks"));
     }
 
-    public void testSpaceNotAllowedInIdPattern() throws Exception {
+    public void testSpaceNotAllowedInIdPattern() {
         expectError("ROW a = 1| RENAME a AS this is `not okay`", "mismatched input 'is' expecting {<EOF>, '|', ',', '.'}");
     }
 
-    public void testSpaceNotAllowedInIdPatternKeep() throws Exception {
+    public void testSpaceNotAllowedInIdPatternKeep() {
         expectError("ROW a = 1, b = 1| KEEP a b", "extraneous input 'b'");
     }
 
@@ -2947,13 +2948,20 @@ public void testNamedFunctionArgumentWithUnsupportedNamedParameterTypes() {
         }
     }
 
-    public void testValidJoinPattern() {
+    public void testValidFromPattern() {
         var basePattern = randomIndexPatterns();
-        var joinPattern = randomIndexPattern(without(WILDCARD_PATTERN));
+
+        var plan = statement("FROM " + basePattern);
+
+        assertThat(as(plan, UnresolvedRelation.class).table().index(), equalTo(unquoteIndexPattern(basePattern)));
+    }
+
+    public void testValidJoinPattern() {
+        var basePattern = randomIndexPatterns(without(CROSS_CLUSTER));
+        var joinPattern = randomIndexPattern(without(WILDCARD_PATTERN), without(CROSS_CLUSTER));
         var onField = randomIdentifier();
-        var type = randomFrom("", "LOOKUP ");
 
-        var plan = statement("FROM " + basePattern + " | " + type + " JOIN " + joinPattern + " ON " + onField);
+        var plan = statement("FROM " + basePattern + " | LOOKUP JOIN " + joinPattern + " ON " + onField);
 
         var join = as(plan, LookupJoin.class);
         assertThat(as(join.left(), UnresolvedRelation.class).table().index(), equalTo(unquoteIndexPattern(basePattern)));
@@ -2966,10 +2974,30 @@ public void testValidJoinPattern() {
     }
 
     public void testInvalidJoinPatterns() {
-        var joinPattern = randomIndexPattern(WILDCARD_PATTERN);
-        expectError(
-            "FROM " + randomIndexPatterns() + " | JOIN " + joinPattern + " ON " + randomIdentifier(),
-            "invalid index pattern [" + unquoteIndexPattern(joinPattern) + "], * is not allowed in LOOKUP JOIN"
-        );
+        {
+            // wildcard
+            var joinPattern = randomIndexPattern(WILDCARD_PATTERN, without(CROSS_CLUSTER));
+            expectError(
+                "FROM " + randomIndexPatterns() + " | LOOKUP JOIN " + joinPattern + " ON " + randomIdentifier(),
+                "invalid index pattern [" + unquoteIndexPattern(joinPattern) + "], * is not allowed in LOOKUP JOIN"
+            );
+        }
+        {
+            // remote cluster on the right
+            var joinPattern = randomIndexPattern(CROSS_CLUSTER, without(WILDCARD_PATTERN));
+            expectError(
+                "FROM " + randomIndexPatterns() + " | LOOKUP JOIN " + joinPattern + " ON " + randomIdentifier(),
+                "invalid index pattern [" + unquoteIndexPattern(joinPattern) + "], remote clusters are not supported in LOOKUP JOIN"
+            );
+        }
+        {
+            // remote cluster on the left
+            var fromPatterns = randomIndexPatterns(CROSS_CLUSTER, without(WILDCARD_PATTERN));
+            var joinPattern = randomIndexPattern(without(CROSS_CLUSTER), without(WILDCARD_PATTERN));
+            expectError(
+                "FROM " + fromPatterns + " | LOOKUP JOIN " + joinPattern + " ON " + randomIdentifier(),
+                "invalid index pattern [" + unquoteIndexPattern(fromPatterns) + "], remote clusters are not supported in LOOKUP JOIN"
+            );
+        }
     }
 }