1 /*
2 * Copyright 2010 The Apache Software Foundation
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20 package org.apache.hadoop.hbase.coprocessor;
21
22 import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;
23 import java.io.IOException;
24
25 /**
26 * A sample protocol for performing aggregation at regions.
27 */
28 public interface ColumnAggregationProtocol extends CoprocessorProtocol {
29 /**
30 * Perform aggregation for a given column at the region. The aggregation
31 * will include all the rows inside the region. It can be extended to
32 * allow passing start and end rows for a fine-grained aggregation.
33 * @param family family
34 * @param qualifier qualifier
35 * @return Aggregation of the column.
36 * @throws exception.
37 */
38 public long sum(byte[] family, byte[] qualifier) throws IOException;
39 }