Add a new rule PinotSeminJoinDistinctProjectRule to apply a distinct …

…to a semi join right side project

pinot-query-planner/src/main/java/org/apache/pinot/calcite/rel/rules/PinotQueryRuleSets.java

@@ -73,6 +73,7 @@ private PinotQueryRuleSets() {
 
       // join and semi-join rules
       CoreRules.PROJECT_TO_SEMI_JOIN,
+      PinotSeminJoinDistinctProjectRule.INSTANCE,
 
       // convert non-all union into all-union + distinct
       CoreRules.UNION_TO_DISTINCT,

pinot-query-planner/src/main/java/org/apache/pinot/calcite/rel/rules/PinotSeminJoinDistinctProjectRule.java

@@ -0,0 +1,68 @@
+/**
+ * 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.pinot.calcite.rel.rules;
+
+import java.util.List;
+import org.apache.calcite.plan.RelOptRule;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.JoinRelType;
+import org.apache.calcite.rel.logical.LogicalJoin;
+import org.apache.calcite.rel.logical.LogicalProject;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.calcite.tools.RelBuilderFactory;
+
+
+/**
+ * Special rule for Pinot, this rule always append a distinct to the
+ * {@link org.apache.calcite.rel.logical.LogicalProject} on top of a Semi join
+ * {@link org.apache.calcite.rel.core.Join} to ensure the correctness of the query.
+ */
+public class PinotSeminJoinDistinctProjectRule extends RelOptRule {
+  public static final PinotSeminJoinDistinctProjectRule INSTANCE =
+      new PinotSeminJoinDistinctProjectRule(PinotRuleUtils.PINOT_REL_FACTORY);
+
+  public PinotSeminJoinDistinctProjectRule(RelBuilderFactory factory) {
+    super(operand(LogicalJoin.class, some(operand(LogicalProject.class, any()), operand(LogicalProject.class, any()))),
+        factory, null);
+  }
+
+  @Override
+  public void onMatch(RelOptRuleCall call) {
+    LogicalJoin join = call.rel(0);
+    if (join.getJoinType() != JoinRelType.SEMI) {
+      return;
+    }
+    LogicalProject leftProject = call.rel(1);
+    LogicalProject rightProject = call.rel(2);
+
+    if (rightProject.getProjects().size() != 1) {
+      return;
+    }
+    RelNode newRightProject = insertDistinctToProject(call, rightProject);
+    call.transformTo(join.copy(join.getTraitSet(), List.of(leftProject, newRightProject)));
+  }
+
+  private RelNode insertDistinctToProject(RelOptRuleCall call, LogicalProject project) {
+    RelBuilder relBuilder = call.builder();
+    relBuilder.push(project);
+    relBuilder.distinct();
+    return relBuilder.build();
+  }
+}