| /** |
| * 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.hadoop.yarn.server.timelineservice.storage.common; |
| |
| /** |
| * In queries where a single result is needed, an exact rowkey can be used |
| * through the corresponding rowkey#getRowKey() method. For queries that need to |
| * scan over a range of rowkeys, a partial (the initial part) of rowkeys are |
| * used. Classes implementing RowKeyPrefix indicate that they are the initial |
| * part of rowkeys, with different constructors with fewer number of argument to |
| * form a partial rowkey, a prefix. |
| * |
| * @param <R> indicating the type of rowkey that a particular implementation is |
| * a prefix for. |
| */ |
| public interface RowKeyPrefix<R> { |
| |
| /** |
| * Create a row key prefix, meaning a partial rowkey that can be used in range |
| * scans. Which fields are included in the prefix will depend on the |
| * constructor of the specific instance that was used. Output depends on which |
| * constructor was used. |
| * @return a prefix of the following form {@code fist!second!...!last!} |
| */ |
| byte[] getRowKeyPrefix(); |
| |
| } |
