Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3354#discussion_r102226285
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/builtInAggFuncs/AvgAggFunction.scala
---
@@ -0,0 +1,268 @@
+/*
+ * 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.functions.builtInAggFuncs
+
+import java.math.{BigDecimal, BigInteger}
+import org.apache.flink.table.functions.{Accumulator, AggregateFunction}
+
+/**
+ * Base class for built-in Integral Avg aggregate function
+ *
+ * @tparam T the type for the aggregation result
+ */
+abstract class IntegralAvgAggFunction[T] extends AggregateFunction[T] {
+ /** The initial accumulator for Integral Avg aggregate function */
+ class IntegralAvgAccumulator extends Accumulator {
--- End diff --
This will be probably handled as a Pojo type which is less efficient than a
`Tuple2`
We can define this as
```
import org.apache.flink.api.java.tuple.{Tuple2 => JTuple2} // use Java
tuple because it's mutable.
class IntegralAvgAccumulator extends JTuple2[Long, Long] with Accumulator
```
which means that Flink can handle it as a Tuple which is more efficient
than a POJO which accesses fields (for de/serialization) via reflection.
I think this implementation will also be closer to the code-gen'd version.
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