Github user huawei-flink commented on a diff in the pull request:
https://github.com/apache/flink/pull/3443#discussion_r103920777
--- Diff:
flink-libraries/flink-table/src/main/java/org/apache/flink/table/plan/nodes/datastream/aggs/DoubleSummaryAggregation.java
---
@@ -0,0 +1,214 @@
+/*
+ * 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.flink.table.plan.nodes.datastream.aggs;
+
+import static
org.apache.flink.api.java.summarize.aggregation.CompensatedSum.ZERO;
+
+import org.apache.flink.api.java.summarize.aggregation.Aggregator;
+import org.apache.flink.api.java.summarize.aggregation.CompensatedSum;
+import
org.apache.flink.api.java.summarize.aggregation.NumericSummaryAggregator;
+
+public class DoubleSummaryAggregation extends
NumericSummaryAggregator<Double> {
--- End diff --
I see that the AggregateFunction interface does not have a reset method if
not the createAccumulator(), this means that we have to create an accumulator
for every apply execution. With the reset you just assign the value to the
starting point, without creating a new object all time. What do you think?
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