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;
  
  import org.apache.calcite.util.mapping.IntPair;
  
  import java.util.List;
  
  /**
   * Interface for a referential constraint, i.e., Foreign-Key - Unique-Key relationship,
   * between two tables.
   */
  public interface RelReferentialConstraint {
    //~ Methods ----------------------------------------------------------------
  
    /** Returns the number of columns in the keys.
     *
     * @deprecated Use {@code getColumnPairs().size()} */
    @Deprecated // to be removed before 2.0
    default int getNumColumns() {
      return getColumnPairs().size();
    }
  
    /**The qualified name of the referencing table, e.g. DEPT. */
    List<String> getSourceQualifiedName();
  
    /** The qualified name of the referenced table, e.g. EMP. */
    List<String> getTargetQualifiedName();
  
    /** The (source, target) column ordinals. */
    List<IntPair> getColumnPairs();
  
  }
  