[CALCITE-6836] Add Rule to convert INTERSECT to EXISTS

core/src/main/java/org/apache/calcite/rel/rules/CoreRules.java

@@ -16,6 +16,7 @@
  */
 package org.apache.calcite.rel.rules;
 
+import org.apache.calcite.plan.RelOptUtil.Exists;
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.core.Aggregate;
 import org.apache.calcite.rel.core.Calc;
@@ -348,6 +349,11 @@ private CoreRules() {}
   public static final IntersectToDistinctRule INTERSECT_TO_DISTINCT =
       IntersectToDistinctRule.Config.DEFAULT.toRule();
 
+  /** Rule that translates a {@link Intersect}
+   * into a {@link Exists} subquery. */
+  public static final IntersectToExistsRule INTERSECT_TO_EXISTS =
+      IntersectToExistsRule.Config.DEFAULT.toRule();
+
   /** Rule that translates a distinct
    * {@link Minus} into a group of operators
    * composed of {@link Union}, {@link Aggregate}, etc. */

core/src/main/java/org/apache/calcite/rel/rules/IntersectToExistsRule.java

@@ -0,0 +1,164 @@
+/*
+ * 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.calcite.rel.rules;
+
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.plan.RelOptUtil.Exists;
+import org.apache.calcite.plan.RelRule;
+import org.apache.calcite.plan.hep.HepRelVertex;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.CorrelationId;
+import org.apache.calcite.rel.core.Intersect;
+import org.apache.calcite.rel.logical.LogicalIntersect;
+import org.apache.calcite.rel.type.RelDataTypeField;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.rex.RexSubQuery;
+import org.apache.calcite.rex.RexUtil;
+import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.calcite.tools.RelBuilderFactory;
+
+import com.google.common.collect.ImmutableSet;
+
+import org.immutables.value.Value;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * Planner rule that translates a {@link Intersect}
+ * (<code>all</code> = <code>false</code>)
+ * into a {@link Exists}.
+ *
+ * @see CoreRules#INTERSECT_TO_EXISTS
+ */
+@Value.Enclosing
+public class IntersectToExistsRule
+    extends RelRule<IntersectToExistsRule.Config>
+    implements TransformationRule {
+
+  /** Creates an IntersectToExistRule. */
+  protected IntersectToExistsRule(Config config) {
+    super(config);
+  }
+
+  @Deprecated // to be removed before 2.0
+  public IntersectToExistsRule(Class<? extends Intersect> intersectClass,
+      RelBuilderFactory relBuilderFactory) {
+    this(Config.DEFAULT.withRelBuilderFactory(relBuilderFactory)
+        .as(Config.class)
+        .withOperandFor(intersectClass));
+  }
+
+  //~ Methods ----------------------------------------------------------------
+
+  @Override public void onMatch(RelOptRuleCall call) {
+    final Intersect intersect = call.rel(0);
+    final RelBuilder builder = call.builder();
+    final RexBuilder rexBuilder = builder.getRexBuilder();
+
+    // Recursive processing of all inputs as logical operators
+    List<RelNode> inputs = new ArrayList<>();
+    for (RelNode rel : intersect.getInputs()) {
+      inputs.add(toLogicalRel(rel));
+    }
+
+    // Get all column indices of intersect
+    List<Integer> fieldIndices = intersect.getRowType().getFieldList()
+        .stream().map(RelDataTypeField::getIndex)
+        .collect(Collectors.toList());
+
+    RelNode current = inputs.get(0);
+
+    // Iterate over the inputs and apply EXISTS subquery
+    for (int i = 1; i < inputs.size(); i++) {
+      RelNode nextInput = inputs.get(i);
+
+      // Create correlation variable
+      CorrelationId correlationId = intersect.getCluster().createCorrel();
+      RexNode correlVariable =
+          rexBuilder.makeCorrel(nextInput.getRowType(), correlationId);
+
+      // Create EXISTS subquery condition
+      List<RexNode> conditions = new ArrayList<>();
+      for (int fieldIndex : fieldIndices) {
+        RexNode outerField = rexBuilder.makeInputRef(current, fieldIndex);
+        RexNode innerField =
+            rexBuilder.makeFieldAccess(correlVariable, fieldIndex);
+        conditions.add(
+            rexBuilder.makeCall(SqlStdOperatorTable.EQUALS,
+                outerField, innerField));
+      }
+      RexNode condition = RexUtil.composeConjunction(rexBuilder, conditions);
+
+      // Build EXISTS subquery
+      RelNode existsSubQuery = builder.push(nextInput)
+          .filter(condition)
+          .project(builder.fields(fieldIndices))
+          .build();
+
+      // Apply EXISTS subquery to the current relation
+      current = builder.push(current)
+          .filter(ImmutableSet.of(correlationId),
+              RexSubQuery.exists(existsSubQuery))
+          .build();
+    }
+
+    RelNode result = builder.push(current)
+        .project(builder.fields(fieldIndices))
+        .distinct()
+        .build();
+
+    call.transformTo(result);
+  }
+
+  /**
+   * Recursively convert RelNodes into logical operators.
+   *
+   * @param node Relnode that may contain HepRelVertex
+   * @return Relnode only contains Logical RelNode */
+  private RelNode toLogicalRel(RelNode node) {
+    if (node instanceof HepRelVertex) {
+      node = ((HepRelVertex) node).getCurrentRel();
+      List<RelNode> inputs = new ArrayList<>();
+      for (RelNode input : node.getInputs()) {
+        inputs.add(toLogicalRel(input));
+      }
+      return node.copy(node.getTraitSet(), inputs);
+    }
+    throw new AssertionError("Not support type " + node.getClass());
+  }
+
+  /** Rule configuration. */
+  @Value.Immutable
+  public interface Config extends RelRule.Config {
+    Config DEFAULT = ImmutableIntersectToExistsRule.Config.of()
+        .withOperandFor(LogicalIntersect.class);
+
+    @Override default IntersectToExistsRule toRule() {
+      return new IntersectToExistsRule(this);
+    }
+
+    /** Defines an operand tree for the given classes. */
+    default Config withOperandFor(Class<? extends Intersect> intersectClass) {
+      return withOperandSupplier(b -> b.operand(intersectClass).anyInputs())
+          .as(Config.class);
+    }
+  }
+}

core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java

@@ -9585,4 +9585,12 @@ private void checkJoinAssociateRuleWithTopAlwaysTrueCondition(boolean allowAlway
         .withRule(CoreRules.MULTI_JOIN_OPTIMIZE)
         .check();
   }
+
+  @Test void testIntersectToExistsRule() {
+    String sql = "SELECT a.deptno FROM dept AS a\n"
+            + "INTERSECT\n"
+            + "SELECT b.empno FROM emp AS b";
+    sql(sql).withRule(CoreRules.INTERSECT_TO_EXISTS)
+            .check();
+  }
 }

core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml

@@ -5440,6 +5440,33 @@ LogicalIntersect(all=[true])
   LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
     LogicalFilter(condition=[=($7, 30)])
       LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testIntersectToExistsRule">
+    <Resource name="sql">
+      <![CDATA[SELECT a.deptno FROM dept AS a
+INTERSECT
+SELECT b.empno FROM emp AS b]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalIntersect(all=[false])
+  LogicalProject(DEPTNO=[$0])
+    LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
+  LogicalProject(EMPNO=[$0])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+    <Resource name="planAfter">
+      <![CDATA[
+LogicalFilter(condition=[EXISTS({
+LogicalFilter(condition=[=($0, $cor0.EMPNO)])
+  LogicalProject(EMPNO=[$0])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+})], variablesSet=[[$cor0]])
+  LogicalProject(DEPTNO=[$0])
+    LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
 ]]>
     </Resource>
   </TestCase>