EnumerableLimitSortRule.java

/*
 * 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.adapter.enumerable;

import org.apache.calcite.plan.RelOptRuleCall;
import org.apache.calcite.plan.RelRule;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.Sort;
import org.apache.calcite.rel.logical.LogicalSort;

import org.immutables.value.Value;

/**
 * Rule to convert an {@link LogicalSort} with ({@link LogicalSort#fetch}
 * or {@link LogicalSort#offset}) and {@link LogicalSort#collation}(Order By)
 * into an {@link EnumerableLimitSort}.
 */
@Value.Enclosing
public class EnumerableLimitSortRule extends RelRule<EnumerableLimitSortRule.Config> {

  /**
   * Creates a EnumerableLimitSortRule.
   */
  public EnumerableLimitSortRule(Config config) {
    super(config);
  }

  @Override public void onMatch(RelOptRuleCall call) {
    final Sort sort = call.rel(0);
    RelNode input = sort.getInput();
    final Sort o =
        EnumerableLimitSort.create(
            convert(call.getPlanner(), input,
                input.getTraitSet().replace(EnumerableConvention.INSTANCE)),
            sort.getCollation(), sort.offset, sort.fetch);

    call.transformTo(o);
  }

  /** Rule configuration. */
  @Value.Immutable
  public interface Config extends RelRule.Config {
    Config DEFAULT =
        ImmutableEnumerableLimitSortRule.Config.of()
            .withOperandSupplier(b0 ->
                b0.operand(LogicalSort.class)
                    .predicate(sort -> (sort.fetch != null || sort.offset != null)
                        && !sort.collation.getFieldCollations().isEmpty())
                    .anyInputs());

    @Override default EnumerableLimitSortRule toRule() {
      return new EnumerableLimitSortRule(this);
    }
  }
}