1 /**
2 *
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 */
19 package org.apache.hadoop.hbase.mapred;
20
21 import java.io.IOException;
22
23 import org.apache.hadoop.hbase.classification.InterfaceAudience;
24 import org.apache.hadoop.hbase.classification.InterfaceStability;
25 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
26 import org.apache.hadoop.hbase.client.Result;
27 import org.apache.hadoop.mapred.JobConf;
28 import org.apache.hadoop.mapred.MapReduceBase;
29 import org.apache.hadoop.mapred.OutputCollector;
30 import org.apache.hadoop.mapred.Reporter;
31
32 /**
33 * Pass the given key and record as-is to reduce
34 */
35 @InterfaceAudience.Public
36 @InterfaceStability.Stable
37 public class IdentityTableMap
38 extends MapReduceBase
39 implements TableMap<ImmutableBytesWritable, Result> {
40
41 /** constructor */
42 public IdentityTableMap() {
43 super();
44 }
45
46 /**
47 * Use this before submitting a TableMap job. It will
48 * appropriately set up the JobConf.
49 *
50 * @param table table name
51 * @param columns columns to scan
52 * @param mapper mapper class
53 * @param job job configuration
54 */
55 @SuppressWarnings("unchecked")
56 public static void initJob(String table, String columns,
57 Class<? extends TableMap> mapper, JobConf job) {
58 TableMapReduceUtil.initTableMapJob(table, columns, mapper,
59 ImmutableBytesWritable.class,
60 Result.class, job);
61 }
62
63 /**
64 * Pass the key, value to reduce
65 * @param key
66 * @param value
67 * @param output
68 * @param reporter
69 * @throws IOException
70 */
71 public void map(ImmutableBytesWritable key, Result value,
72 OutputCollector<ImmutableBytesWritable,Result> output,
73 Reporter reporter) throws IOException {
74
75 // convert
76 output.collect(key, value);
77 }
78 }