001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019package org.apache.hadoop.mapred.lib; 020 021import org.apache.hadoop.classification.InterfaceAudience; 022import org.apache.hadoop.classification.InterfaceStability; 023import org.apache.hadoop.mapred.JobConf; 024import org.apache.hadoop.mapred.JobConfigurable; 025import org.apache.hadoop.mapreduce.JobContext; 026 027/** 028 * This comparator implementation provides a subset of the features provided 029 * by the Unix/GNU Sort. In particular, the supported features are: 030 * -n, (Sort numerically) 031 * -r, (Reverse the result of comparison) 032 * -k pos1[,pos2], where pos is of the form f[.c][opts], where f is the number 033 * of the field to use, and c is the number of the first character from the 034 * beginning of the field. Fields and character posns are numbered starting 035 * with 1; a character position of zero in pos2 indicates the field's last 036 * character. If '.c' is omitted from pos1, it defaults to 1 (the beginning 037 * of the field); if omitted from pos2, it defaults to 0 (the end of the 038 * field). opts are ordering options (any of 'nr' as described above). 039 * We assume that the fields in the key are separated by 040 * {@link JobContext#MAP_OUTPUT_KEY_FIELD_SEPERATOR} 041 */ 042@InterfaceAudience.Public 043@InterfaceStability.Stable 044public class KeyFieldBasedComparator<K, V> extends 045 org.apache.hadoop.mapreduce.lib.partition.KeyFieldBasedComparator<K, V> 046 implements JobConfigurable { 047 048 public void configure(JobConf job) { 049 super.setConf(job); 050 } 051}