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<pre><span class="source-line-no">001</span><span id="line-1">/*</span>
<span class="source-line-no">002</span><span id="line-2"> * Licensed to the Apache Software Foundation (ASF) under one</span>
<span class="source-line-no">003</span><span id="line-3"> * or more contributor license agreements. See the NOTICE file</span>
<span class="source-line-no">004</span><span id="line-4"> * distributed with this work for additional information</span>
<span class="source-line-no">005</span><span id="line-5"> * regarding copyright ownership. The ASF licenses this file</span>
<span class="source-line-no">006</span><span id="line-6"> * to you under the Apache License, Version 2.0 (the</span>
<span class="source-line-no">007</span><span id="line-7"> * "License"); you may not use this file except in compliance</span>
<span class="source-line-no">008</span><span id="line-8"> * with the License. You may obtain a copy of the License at</span>
<span class="source-line-no">009</span><span id="line-9"> *</span>
<span class="source-line-no">010</span><span id="line-10"> * http://www.apache.org/licenses/LICENSE-2.0</span>
<span class="source-line-no">011</span><span id="line-11"> *</span>
<span class="source-line-no">012</span><span id="line-12"> * Unless required by applicable law or agreed to in writing, software</span>
<span class="source-line-no">013</span><span id="line-13"> * distributed under the License is distributed on an "AS IS" BASIS,</span>
<span class="source-line-no">014</span><span id="line-14"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
<span class="source-line-no">015</span><span id="line-15"> * See the License for the specific language governing permissions and</span>
<span class="source-line-no">016</span><span id="line-16"> * limitations under the License.</span>
<span class="source-line-no">017</span><span id="line-17"> */</span>
<span class="source-line-no">018</span><span id="line-18">package org.apache.hadoop.hbase.mapreduce;</span>
<span class="source-line-no">019</span><span id="line-19"></span>
<span class="source-line-no">020</span><span id="line-20">import java.io.IOException;</span>
<span class="source-line-no">021</span><span id="line-21">import org.apache.hadoop.hbase.client.Mutation;</span>
<span class="source-line-no">022</span><span id="line-22">import org.apache.hadoop.io.Writable;</span>
<span class="source-line-no">023</span><span id="line-23">import org.apache.yetus.audience.InterfaceAudience;</span>
<span class="source-line-no">024</span><span id="line-24">import org.slf4j.Logger;</span>
<span class="source-line-no">025</span><span id="line-25">import org.slf4j.LoggerFactory;</span>
<span class="source-line-no">026</span><span id="line-26"></span>
<span class="source-line-no">027</span><span id="line-27">/**</span>
<span class="source-line-no">028</span><span id="line-28"> * Convenience class that simply writes all values (which must be</span>
<span class="source-line-no">029</span><span id="line-29"> * {@link org.apache.hadoop.hbase.client.Put Put} or {@link org.apache.hadoop.hbase.client.Delete</span>
<span class="source-line-no">030</span><span id="line-30"> * Delete} instances) passed to it out to the configured HBase table. This works in combination with</span>
<span class="source-line-no">031</span><span id="line-31"> * {@link TableOutputFormat} which actually does the writing to HBase.</span>
<span class="source-line-no">032</span><span id="line-32"> * &lt;p&gt;</span>
<span class="source-line-no">033</span><span id="line-33"> * Keys are passed along but ignored in TableOutputFormat. However, they can be used to control how</span>
<span class="source-line-no">034</span><span id="line-34"> * your values will be divided up amongst the specified number of reducers.</span>
<span class="source-line-no">035</span><span id="line-35"> * &lt;p&gt;</span>
<span class="source-line-no">036</span><span id="line-36"> * You can also use the {@link TableMapReduceUtil} class to set up the two classes in one step:</span>
<span class="source-line-no">037</span><span id="line-37"> * &lt;blockquote&gt;&lt;code&gt;</span>
<span class="source-line-no">038</span><span id="line-38"> * TableMapReduceUtil.initTableReducerJob("table", IdentityTableReducer.class, job);</span>
<span class="source-line-no">039</span><span id="line-39"> * &lt;/code&gt;&lt;/blockquote&gt; This will also set the proper {@link TableOutputFormat} which is given the</span>
<span class="source-line-no">040</span><span id="line-40"> * &lt;code&gt;table&lt;/code&gt; parameter. The {@link org.apache.hadoop.hbase.client.Put Put} or</span>
<span class="source-line-no">041</span><span id="line-41"> * {@link org.apache.hadoop.hbase.client.Delete Delete} define the row and columns implicitly.</span>
<span class="source-line-no">042</span><span id="line-42"> */</span>
<span class="source-line-no">043</span><span id="line-43">@InterfaceAudience.Public</span>
<span class="source-line-no">044</span><span id="line-44">public class IdentityTableReducer extends TableReducer&lt;Writable, Mutation, Writable&gt; {</span>
<span class="source-line-no">045</span><span id="line-45"></span>
<span class="source-line-no">046</span><span id="line-46"> @SuppressWarnings("unused")</span>
<span class="source-line-no">047</span><span id="line-47"> private static final Logger LOG = LoggerFactory.getLogger(IdentityTableReducer.class);</span>
<span class="source-line-no">048</span><span id="line-48"></span>
<span class="source-line-no">049</span><span id="line-49"> /**</span>
<span class="source-line-no">050</span><span id="line-50"> * Writes each given record, consisting of the row key and the given values, to the configured</span>
<span class="source-line-no">051</span><span id="line-51"> * {@link org.apache.hadoop.mapreduce.OutputFormat}. It is emitting the row key and each</span>
<span class="source-line-no">052</span><span id="line-52"> * {@link org.apache.hadoop.hbase.client.Put Put} or {@link org.apache.hadoop.hbase.client.Delete</span>
<span class="source-line-no">053</span><span id="line-53"> * Delete} as separate pairs.</span>
<span class="source-line-no">054</span><span id="line-54"> * @param key The current row key.</span>
<span class="source-line-no">055</span><span id="line-55"> * @param values The {@link org.apache.hadoop.hbase.client.Put Put} or</span>
<span class="source-line-no">056</span><span id="line-56"> * {@link org.apache.hadoop.hbase.client.Delete Delete} list for the given row.</span>
<span class="source-line-no">057</span><span id="line-57"> * @param context The context of the reduce.</span>
<span class="source-line-no">058</span><span id="line-58"> * @throws IOException When writing the record fails.</span>
<span class="source-line-no">059</span><span id="line-59"> * @throws InterruptedException When the job gets interrupted.</span>
<span class="source-line-no">060</span><span id="line-60"> */</span>
<span class="source-line-no">061</span><span id="line-61"> @Override</span>
<span class="source-line-no">062</span><span id="line-62"> public void reduce(Writable key, Iterable&lt;Mutation&gt; values, Context context)</span>
<span class="source-line-no">063</span><span id="line-63"> throws IOException, InterruptedException {</span>
<span class="source-line-no">064</span><span id="line-64"> for (Mutation putOrDelete : values) {</span>
<span class="source-line-no">065</span><span id="line-65"> context.write(key, putOrDelete);</span>
<span class="source-line-no">066</span><span id="line-66"> }</span>
<span class="source-line-no">067</span><span id="line-67"> }</span>
<span class="source-line-no">068</span><span id="line-68">}</span>
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