/*
* 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.eigenbase.rel;
import java.util.*;
import org.eigenbase.relopt.RelTrait;
/**
* Description of the physical ordering of a relational expression.
*
* <p>An ordering consists of a list of one or more column ordinals and the
* direction of the ordering.
*/
public interface RelCollation extends RelTrait {
//~ Methods ----------------------------------------------------------------
/**
* Returns the ordinals and directions of the columns in this ordering.
*/
List<RelFieldCollation> getFieldCollations();
}
// End RelCollation.java