[hotfix] Normalize Calcite correlation variables

flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/plan/optimize/CorrelVariableNormalizerShuttle.java

@@ -0,0 +1,119 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.planner.plan.optimize;
+
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.RelShuttleImpl;
+import org.apache.calcite.rel.core.CorrelationId;
+import org.apache.calcite.rel.logical.LogicalCorrelate;
+import org.apache.calcite.rel.logical.LogicalTableFunctionScan;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexCorrelVariable;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.rex.RexShuttle;
+import org.apache.calcite.rex.RexSubQuery;
+
+import java.util.Optional;
+
+public final class CorrelVariableNormalizerShuttle extends RelShuttleImpl {
+
+    private final RexBuilder rexBuilder;
+    private final RexShuttle rexCorrelNormalizer;
+
+    private int correlationIdAdjustment = Integer.MIN_VALUE;
+
+    public CorrelVariableNormalizerShuttle(RexBuilder rexBuilder) {
+        this.rexBuilder = rexBuilder;
+        rexCorrelNormalizer = new RexCorrelNormalizer();
+    }
+
+    @Override
+    public RelNode visit(LogicalCorrelate correlate) {
+        var adjustedId = adjustCorrelationId(correlate.getCorrelationId());
+        if (adjustedId.isPresent()) {
+            var left = correlate.getLeft().accept(this);
+            var right = correlate.getRight().accept(this);
+            return correlate.copy(
+                    correlate.getTraitSet(),
+                    left,
+                    right,
+                    adjustedId.get(),
+                    correlate.getRequiredColumns(),
+                    correlate.getJoinType());
+        }
+
+        return super.visit(correlate);
+    }
+
+    @Override
+    public RelNode visit(RelNode relNode) {
+        if (relNode instanceof LogicalTableFunctionScan && relNode.getInputs().isEmpty()) {
+            // Since we only visit the children with the rexshuttle below,
+            // we have to explicitly visit the table function scan since it is a sink (i.e. no
+            // children) but can have RexNodes (a TableScan cannot)
+            return relNode.accept(rexCorrelNormalizer);
+        }
+
+        return super.visit(relNode);
+    }
+
+    @Override
+    protected RelNode visitChild(RelNode parent, int i, RelNode child) {
+        if (i == 0) {
+            parent = parent.accept(rexCorrelNormalizer);
+        }
+
+        return super.visitChild(parent, i, child);
+    }
+
+    private Optional<CorrelationId> adjustCorrelationId(CorrelationId correlationId) {
+        if (!correlationId.getName().startsWith(CorrelationId.CORREL_PREFIX)) {
+            return Optional.empty();
+        }
+
+        if (correlationIdAdjustment < 0) {
+            correlationIdAdjustment = correlationId.getId() - 1;
+        }
+
+        if (correlationIdAdjustment == 0) {
+            return Optional.empty();
+        }
+
+        return Optional.of(new CorrelationId(correlationId.getId() - correlationIdAdjustment));
+    }
+
+    private final class RexCorrelNormalizer extends RexShuttle {
+
+        @Override
+        public RexNode visitCorrelVariable(RexCorrelVariable variable) {
+            var adjustedId = adjustCorrelationId(variable.id);
+            if (adjustedId.isPresent()) {
+                return rexBuilder.makeCorrel(variable.getType(), adjustedId.get());
+            } else {
+                return super.visitCorrelVariable(variable);
+            }
+        }
+
+        @Override
+        public RexNode visitSubQuery(RexSubQuery subQuery) {
+            var rewritten = subQuery.rel.accept(CorrelVariableNormalizerShuttle.this);
+            return subQuery.clone(rewritten);
+        }
+    }
+}

flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/planner/plan/optimize/CommonSubGraphBasedOptimizer.scala

@@ -84,7 +84,14 @@ abstract class CommonSubGraphBasedOptimizer extends Optimizer {
     val clearQueryBlockAliasResolver = new ClearQueryBlockAliasResolver
     val resolvedAliasRoots = clearQueryBlockAliasResolver.resolve(resolvedHintRoots)
 
-    val sinkBlocks = doOptimize(resolvedAliasRoots)
+    // Normalize correlation variable ids per root so structurally equivalent
+    // subplans across sinks share digests (required for SubplanReuser to dedupe).
+    // A fresh shuttle per root avoids the first root's adjustment leaking into
+    // the next one's numbering.
+    val normalizedRoots = resolvedAliasRoots.map(
+      root => root.accept(new CorrelVariableNormalizerShuttle(root.getCluster.getRexBuilder)))
+
+    val sinkBlocks = doOptimize(normalizedRoots)
     val optimizedPlan = sinkBlocks.map {
       block =>
         val plan = block.getOptimizedPlan