InnodbSort.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.innodb;

import org.apache.calcite.plan.RelOptCluster;
import org.apache.calcite.plan.RelOptCost;
import org.apache.calcite.plan.RelOptPlanner;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelCollation;
import org.apache.calcite.rel.RelFieldCollation;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.Sort;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.rex.RexNode;

import org.checkerframework.checker.nullness.qual.Nullable;

import java.util.List;

import static com.google.common.base.Preconditions.checkState;

import static java.util.Objects.requireNonNull;

/**
 * Implementation of {@link org.apache.calcite.rel.core.Sort}
 * relational expression for an InnoDB data source.
 */
public class InnodbSort extends Sort implements InnodbRel {
  InnodbSort(RelOptCluster cluster, RelTraitSet traitSet,
      RelNode input, RelCollation collation) {
    super(cluster, traitSet, input, collation, null, null);

    assert getConvention() == InnodbRel.CONVENTION;
    assert getConvention() == input.getConvention();
  }

  @Override public @Nullable RelOptCost computeSelfCost(RelOptPlanner planner,
      RelMetadataQuery mq) {
    final RelOptCost cost = requireNonNull(super.computeSelfCost(planner, mq));
    if (!collation.getFieldCollations().isEmpty()) {
      return cost.multiplyBy(0.05);
    } else {
      return cost;
    }
  }

  @Override public Sort copy(RelTraitSet traitSet, RelNode input,
      RelCollation newCollation, RexNode offset, RexNode fetch) {
    return new InnodbSort(getCluster(), traitSet, input, collation);
  }

  @Override public void implement(Implementor implementor) {
    implementor.visitChild(0, getInput());

    List<RelFieldCollation> sortCollations = collation.getFieldCollations();
    boolean allDesc = sortCollations.stream().allMatch(r -> r.direction.isDescending());
    boolean allNonDesc = sortCollations.stream().noneMatch(r -> r.direction.isDescending());
    // field collation should be in a series of ascending or descending collations
    checkState(allDesc || allNonDesc, "ordering should be in a "
        + "series of ascending or descending collations " + sortCollations);
    implementor.setAscOrder(!allDesc);
  }
}