| /* |
| * 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.plan; |
| |
| /** |
| * Trait for which a given relational expression can have multiple values. |
| * |
| * <p>The most common example is sorted-ness (collation). The TIME dimension |
| * table might be sorted by [year, month, date] and also by [time_id]. |
| */ |
| public interface RelMultipleTrait |
| extends RelTrait, Comparable<RelMultipleTrait> { |
| /** Returns whether this trait is satisfied by every instance of the trait |
| * (including itself). */ |
| boolean isTop(); |
| } |
