/**
* 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.hive.contrib.mr;
import java.util.Iterator;
/**
* Simple reducer interface.
*/
public interface Reducer {
/**
* Reduce.
*
* Note that it is assumed that the key is the first column. Additionally, the
* key will be repeated as the first column in the records[] array.
*
* @param key
* key (first column) for this set of records.
* @param records
* Iterator of records for this key. Note that the first column of
* record will also be the key.
* @param output
* @throws Exception
*/
void reduce(String key, Iterator<String[]> records, Output output)
throws Exception;
}