| /** |
| * 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.contrib.utils.join; |
| |
| import org.apache.hadoop.io.Text; |
| |
| import org.apache.hadoop.contrib.utils.join.DataJoinMapperBase; |
| import org.apache.hadoop.contrib.utils.join.TaggedMapOutput; |
| import org.apache.hadoop.contrib.utils.join.SampleTaggedMapOutput; |
| |
| /** |
| * This is a subclass of DataJoinMapperBase that is used to |
| * demonstrate the functionality of INNER JOIN between 2 data |
| * sources (TAB separated text files) based on the first column. |
| */ |
| public class SampleDataJoinMapper extends DataJoinMapperBase { |
| |
| |
| protected Text generateInputTag(String inputFile) { |
| // tag the row with input file name (data source) |
| return new Text(inputFile); |
| } |
| |
| protected Text generateGroupKey(TaggedMapOutput aRecord) { |
| // first column in the input tab separated files becomes the key (to perform the JOIN) |
| String line = ((Text) aRecord.getData()).toString(); |
| String groupKey = ""; |
| String[] tokens = line.split("\\t", 2); |
| groupKey = tokens[0]; |
| return new Text(groupKey); |
| } |
| |
| protected TaggedMapOutput generateTaggedMapOutput(Object value) { |
| TaggedMapOutput retv = new SampleTaggedMapOutput((Text) value); |
| retv.setTag(new Text(this.inputTag)); |
| return retv; |
| } |
| } |