/*
*
* 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.hbase.coprocessor;
import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;
import java.io.IOException;
/**
* A sample protocol for performing aggregation at regions.
*/
public interface ColumnAggregationProtocol extends CoprocessorProtocol {
/**
* Perform aggregation for a given column at the region. The aggregation
* will include all the rows inside the region. It can be extended to
* allow passing start and end rows for a fine-grained aggregation.
* @param family family
* @param qualifier qualifier
* @return Aggregation of the column.
* @throws exception.
*/
public long sum(byte[] family, byte[] qualifier) throws IOException;
}