How to use

RelDecorrelator$RemoveSingleAggregateRule

in

org.apache.calcite.sql2rel

public RelNode removeCorrelationViaRule(RelNode root) {
  HepProgram program = HepProgram.builder()
      .addRuleInstance(new RemoveSingleAggregateRule())
      .addRuleInstance(new RemoveCorrelationForScalarProjectRule())
      //.addRuleInstance(new RemoveCorrelationForScalarAggregateRule())
      .build();
  HepPlanner planner = createPlanner(program);
  planner.setRoot(root);
  return planner.findBestExp();
}

RemoveSingleAggregateRule(RelBuilderFactory relBuilderFactory) {
 super(
   operand(
     LogicalAggregate.class,
     operand(
       LogicalProject.class,
       operand(LogicalAggregate.class, any()))),
   relBuilderFactory, null);
}

RemoveSingleAggregateRule(RelBuilderFactory relBuilderFactory) {
 super(
   operand(
     LogicalAggregate.class,
     operand(
       LogicalProject.class,
       operand(LogicalAggregate.class, any()))),
   relBuilderFactory, null);
}

public RelNode removeCorrelationViaRule(RelNode root) {
 final RelBuilderFactory f = relBuilderFactory();
 HepProgram program = HepProgram.builder()
   .addRuleInstance(new RemoveSingleAggregateRule(f))
   .addRuleInstance(new RemoveCorrelationForScalarProjectRule(f))
   .addRuleInstance(new RemoveCorrelationForScalarAggregateRule(f))
   .build();
 HepPlanner planner = createPlanner(program);
 planner.setRoot(root);
 return planner.findBestExp();
}

RemoveSingleAggregateRule() {
  super(
      operand(
          LogicalAggregate.class,
          operand(
              LogicalProject.class,
              operand(LogicalAggregate.class, any()))));
}

public RelNode removeCorrelationViaRule(RelNode root) {
 final RelBuilderFactory f = relBuilderFactory();
 HepProgram program = HepProgram.builder()
   .addRuleInstance(new RemoveSingleAggregateRule(f))
   .addRuleInstance(new RemoveCorrelationForScalarProjectRule(f))
   .addRuleInstance(new RemoveCorrelationForScalarAggregateRule(f))
   .build();
 HepPlanner planner = createPlanner(program);
 planner.setRoot(root);
 return planner.findBestExp();
}