content: /*
   * 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);
    }
  }
  