/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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 eu.stratosphere.test.recordJobs.relational.query9Util;
import java.util.Iterator;
import eu.stratosphere.api.java.record.functions.ReduceFunction;
import eu.stratosphere.types.Record;
import eu.stratosphere.types.StringValue;
import eu.stratosphere.util.Collector;
@SuppressWarnings("serial")
public class AmountAggregate extends ReduceFunction {
private StringValue value = new StringValue();
/**
* Aggregate "amount":
*
* sum(amount)
* GROUP BY nation, year
*
* Output Schema:
* Key: (nation, year)
* Value: amount
*
*/
@Override
public void reduce(Iterator<Record> records, Collector<Record> out) throws Exception
{
Record record = null;
float amount = 0;
while (records.hasNext()) {
record = records.next();
StringValue value = record.getField(1, StringValue.class);
amount += Float.parseFloat(value.toString());
}
value.setValue(String.valueOf(amount));
record.setField(1, value);
out.collect(record);
}
/**
* Creates partial sums of "amount" for each data batch:
*/
@Override
public void combine(Iterator<Record> records, Collector<Record> out) throws Exception
{
reduce(records, out);
}
}