1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.shardingsphere.sharding.merge.dql.groupby.aggregation;
19
20 import lombok.RequiredArgsConstructor;
21
22 import java.math.BigDecimal;
23 import java.math.RoundingMode;
24 import java.util.List;
25
26 /**
27 * Average aggregation unit.
28 */
29 @RequiredArgsConstructor
30 public final class AverageAggregationUnit implements AggregationUnit {
31
32 private BigDecimal count;
33
34 private BigDecimal sum;
35
36 @Override
37 public void merge(final List<Comparable<?>> values) {
38 if (null == values || null == values.get(0) || null == values.get(1)) {
39 return;
40 }
41 if (null == count) {
42 count = BigDecimal.ZERO;
43 }
44 if (null == sum) {
45 sum = BigDecimal.ZERO;
46 }
47 count = count.add(new BigDecimal(values.get(0).toString()));
48 sum = sum.add(new BigDecimal(values.get(1).toString()));
49 }
50
51 @Override
52 public Comparable<?> getResult() {
53 if (null == count || BigDecimal.ZERO.equals(count)) {
54 return count;
55 }
56 // TODO use metadata to fetch float number precise for database field
57 return sum.divide(count, 4, RoundingMode.HALF_UP);
58 }
59 }