/**
* 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;
}
}