Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/3547#discussion_r106344518
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/aggregate/BoundedProcessingOverWindowFunction.scala
---
@@ -0,0 +1,97 @@
+/*
+ * 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
+ *
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+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ */
+package org.apache.flink.table.runtime.aggregate
+
+import org.apache.flink.api.java.tuple.Tuple
+import org.apache.flink.types.Row
+import org.apache.flink.configuration.Configuration
+import
org.apache.flink.streaming.api.functions.windowing.RichWindowFunction
+import org.apache.flink.streaming.api.windowing.windows.Window
+import org.apache.flink.util.Collector
+import org.apache.flink.table.functions.AggregateFunction
+import org.apache.flink.api.java.typeutils.RowTypeInfo
+import org.apache.flink.util.Preconditions
+import org.apache.flink.table.functions.Accumulator
+import java.lang.Iterable
+
+class BoundedProcessingOverWindowFunction[W <: Window](
--- End diff --
I glad to explain this. IMO. There are several advantages to using
`ProcessFunction`:
1. OverWindow implementation code consistent, such as: FLINK-5803,
FLINK-5804, FLINK-5658 (See @fhueske propose the design in #3386 )
2. Because using `ProcessFunction` can manage their own state, the
management window of the data collection, you can customize the trigger window,
so in the future when the `FOLLOWING` supported we can be very convenient
support.
3. For incremental aggregation, window mechanism must increase the
implementation of `reduceFunction`, `ProcessFunction` in the management of the
state at the same time will be very natural support.
What do you think?
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