Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3574#discussion_r106965219
--- 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 = _
--- End diff --
We cannot save the last record in a member variable. This will be lost in
case of a failure. We have to put it in the accumulator such that it is
checkpointed.
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