| /** |
| * Copyright 2007 The Apache Software Foundation |
| * |
| * 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.hbase.mapreduce; |
| |
| import java.io.IOException; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.mapreduce.OutputFormat; |
| |
| /** |
| * Convenience class that simply writes all values (which must be |
| * {@link org.apache.hadoop.hbase.client.Put Put} or |
| * {@link org.apache.hadoop.hbase.client.Delete Delete} instances) |
| * passed to it out to the configured HBase table. This works in combination |
| * with {@link TableOutputFormat} which actually does the writing to HBase.<p> |
| * |
| * Keys are passed along but ignored in TableOutputFormat. However, they can |
| * be used to control how your values will be divided up amongst the specified |
| * number of reducers. <p> |
| * |
| * You can also use the {@link TableMapReduceUtil} class to set up the two |
| * classes in one step: |
| * <blockquote><code> |
| * TableMapReduceUtil.initTableReducerJob("table", IdentityTableReducer.class, job); |
| * </code></blockquote> |
| * This will also set the proper {@link TableOutputFormat} which is given the |
| * <code>table</code> parameter. The |
| * {@link org.apache.hadoop.hbase.client.Put Put} or |
| * {@link org.apache.hadoop.hbase.client.Delete Delete} define the |
| * row and columns implicitly. |
| */ |
| public class IdentityTableReducer |
| extends TableReducer<Writable, Writable, Writable> { |
| |
| @SuppressWarnings("unused") |
| private static final Log LOG = LogFactory.getLog(IdentityTableReducer.class); |
| |
| /** |
| * Writes each given record, consisting of the row key and the given values, |
| * to the configured {@link OutputFormat}. It is emitting the row key and each |
| * {@link org.apache.hadoop.hbase.client.Put Put} or |
| * {@link org.apache.hadoop.hbase.client.Delete Delete} as separate pairs. |
| * |
| * @param key The current row key. |
| * @param values The {@link org.apache.hadoop.hbase.client.Put Put} or |
| * {@link org.apache.hadoop.hbase.client.Delete Delete} list for the given |
| * row. |
| * @param context The context of the reduce. |
| * @throws IOException When writing the record fails. |
| * @throws InterruptedException When the job gets interrupted. |
| */ |
| @Override |
| public void reduce(Writable key, Iterable<Writable> values, Context context) |
| throws IOException, InterruptedException { |
| for(Writable putOrDelete : values) { |
| context.write(key, putOrDelete); |
| } |
| } |
| } |