Minus.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.rel.core;

import org.apache.calcite.plan.RelOptCluster;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelInput;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.hint.RelHint;
import org.apache.calcite.rel.metadata.RelMdUtil;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.sql.SqlKind;

import java.util.Collections;
import java.util.List;

/**
 * Relational expression that returns the rows of its first input minus any
 * matching rows from its other inputs.
 *
 * <p>Corresponds to the SQL {@code EXCEPT} operator.
 *
 * <p>If "all" is true, then multiset subtraction is
 * performed; otherwise, set subtraction is performed (implying no duplicates in
 * the results).
 */
public abstract class Minus extends SetOp {

  public Minus(RelOptCluster cluster, RelTraitSet traits, List<RelHint> hints,
      List<RelNode> inputs, boolean all) {
    super(cluster, traits, hints, inputs, SqlKind.EXCEPT, all);
  }

  protected Minus(RelOptCluster cluster, RelTraitSet traits, List<RelNode> inputs,
      boolean all) {
    this(cluster, traits, Collections.emptyList(), inputs, all);
  }

  /**
   * Creates a Minus by parsing serialized output.
   */
  protected Minus(RelInput input) {
    super(input);
  }

  @Override public double estimateRowCount(RelMetadataQuery mq) {
    return RelMdUtil.getMinusRowCount(mq, this);
  }
}