/**
* 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.sqoop.mapreduce;
import java.io.IOException;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
import com.cloudera.sqoop.lib.SqoopRecord;
/**
* Reducer for merge tool. Given records tagged as 'old' or 'new', emit
* a new one if possible; otherwise, an old one.
*/
public class MergeReducer
extends Reducer<Text, MergeRecord, SqoopRecord, NullWritable> {
@Override
public void reduce(Text key, Iterable<MergeRecord> vals, Context c)
throws IOException, InterruptedException {
SqoopRecord bestRecord = null;
try {
for (MergeRecord val : vals) {
if (null == bestRecord && !val.isNewRecord()) {
// Use an old record if we don't have a new record.
bestRecord = (SqoopRecord) val.getSqoopRecord().clone();
} else if (val.isNewRecord()) {
bestRecord = (SqoopRecord) val.getSqoopRecord().clone();
}
}
} catch (CloneNotSupportedException cnse) {
throw new IOException(cnse);
}
if (null != bestRecord) {
c.write(bestRecord, NullWritable.get());
}
}
}