1 /** 2 * Copyright 2009 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 package org.apache.hadoop.hbase.mapreduce; 21 22 import java.util.TreeSet; 23 24 import org.apache.hadoop.hbase.KeyValue; 25 import org.apache.hadoop.hbase.io.ImmutableBytesWritable; 26 import org.apache.hadoop.mapreduce.Reducer; 27 28 /** 29 * Emits sorted KeyValues. 30 * Reads in all KeyValues from passed Iterator, sorts them, then emits 31 * KeyValues in sorted order. If lots of columns per row, it will use lots of 32 * memory sorting. 33 * @see HFileOutputFormat 34 */ 35 public class KeyValueSortReducer extends Reducer<ImmutableBytesWritable, KeyValue, ImmutableBytesWritable, KeyValue> { 36 protected void reduce(ImmutableBytesWritable row, java.lang.Iterable<KeyValue> kvs, 37 org.apache.hadoop.mapreduce.Reducer<ImmutableBytesWritable, KeyValue, ImmutableBytesWritable, KeyValue>.Context context) 38 throws java.io.IOException, InterruptedException { 39 TreeSet<KeyValue> map = new TreeSet<KeyValue>(KeyValue.COMPARATOR); 40 for (KeyValue kv: kvs) { 41 map.add(kv.clone()); 42 } 43 context.setStatus("Read " + map.getClass()); 44 int index = 0; 45 for (KeyValue kv: map) { 46 context.write(row, kv); 47 if (index > 0 && index % 100 == 0) context.setStatus("Wrote " + index); 48 } 49 } 50 }