Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3574#discussion_r106966705
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/aggregate/AggregateAggOverFunction.scala
---
@@ -0,0 +1,102 @@
+/*
+ * 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.runtime.aggregate
+
+import java.util.{ArrayList => JArrayList, List => JList}
+import org.apache.flink.api.common.functions.{AggregateFunction =>
DataStreamAggOverFunc}
+import org.apache.flink.table.functions.{Accumulator, AggregateFunction}
+import org.apache.flink.types.Row
+import org.apache.flink.util.Preconditions
+
+/**
+ * Aggregate Function used for the aggregate operator in
+ * [[org.apache.flink.streaming.api.datastream.WindowedStream]]
+ *
+ * @param aggregates the list of all
[[org.apache.flink.table.functions.AggregateFunction]]
+ * used for this aggregation
+ * @param aggFields the position (in the input Row) of the input value
for each aggregate
+ * @param forwardedFieldCount the number of elements in the Row to kept
after the aggregation
+ */
+class AggregateAggOverFunction(
+ private val aggregates: Array[AggregateFunction[_]],
+ private val aggFields: Array[Int],
+ private val forwardedFieldCount: Int)
+ extends DataStreamAggOverFunc[Row, Row, Row] {
+
+ Preconditions.checkNotNull(aggregates)
+ Preconditions.checkNotNull(aggFields)
+ Preconditions.checkArgument(aggregates.length == aggFields.length)
+
+ private var lastVal:Row = _
+
+ override def createAccumulator(): Row = {
+ val accumulatorRow: Row = new Row(aggregates.length)
+ var i = 0
+ while (i < aggregates.length) {
+ accumulatorRow.setField(i, aggregates(i).createAccumulator())
+ i += 1
+ }
+ accumulatorRow
+ }
+
+ override def add(value: Row, accumulatorRow: Row): Unit = {
+ var i = 0
+ while (i < aggregates.length) {
+ val acc = accumulatorRow.getField(i).asInstanceOf[Accumulator]
+ val v = value.getField(aggFields(i))
+ aggregates(i).accumulate(acc, v)
+ i += 1
+ }
+ lastVal = value;
+ }
+
+ override def getResult(accumulatorRow: Row): Row = {
+ val output = new Row(forwardedFieldCount + aggFields.length)
+
+ var i = 0
+ // set the output value of forward fields
+ while (i < forwardedFieldCount) {
+ output.setField(i, lastVal.getField(i))
+ i += 1
+ }
+
+ i = 0
+ while (i < aggregates.length) {
+ val acc = accumulatorRow.getField(i).asInstanceOf[Accumulator]
+ output.setField(forwardedFieldCount + i, aggregates(i).getValue(acc))
+ i += 1
+ }
+ output
+ }
+
+ override def merge(aAccumulatorRow: Row, bAccumulatorRow: Row): Row = {
+
+ var i = 0
+ while (i < aggregates.length) {
--- End diff --
I'm sorry, I just realized that we cannot use the `AggregateFunction`
interface.
We would need to merge the forwarded fields as well. Since we do not know
which accumulator holds the forwarded fields of the last row, it is not
possible to use this interface. I'm sorry that I led you into this direction.
:-(
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