1 /**
2 * Copyright 2007 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.io.IOException;
23
24 import org.apache.hadoop.hbase.client.Result;
25 import org.apache.hadoop.hbase.client.Scan;
26 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
27 import org.apache.hadoop.mapreduce.Job;
28
29 /**
30 * Pass the given key and record as-is to the reduce phase.
31 */
32 public class IdentityTableMapper
33 extends TableMapper<ImmutableBytesWritable, Result> {
34
35 /**
36 * Use this before submitting a TableMap job. It will appropriately set up
37 * the job.
38 *
39 * @param table The table name.
40 * @param scan The scan with the columns to scan.
41 * @param mapper The mapper class.
42 * @param job The job configuration.
43 * @throws IOException When setting up the job fails.
44 */
45 @SuppressWarnings("unchecked")
46 public static void initJob(String table, Scan scan,
47 Class<? extends TableMapper> mapper, Job job) throws IOException {
48 TableMapReduceUtil.initTableMapperJob(table, scan, mapper,
49 ImmutableBytesWritable.class, Result.class, job);
50 }
51
52 /**
53 * Pass the key, value to reduce.
54 *
55 * @param key The current key.
56 * @param value The current value.
57 * @param context The current context.
58 * @throws IOException When writing the record fails.
59 * @throws InterruptedException When the job is aborted.
60 */
61 public void map(ImmutableBytesWritable key, Result value, Context context)
62 throws IOException, InterruptedException {
63 context.write(key, value);
64 }
65
66 }