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https://issues.apache.org/jira/browse/FLINK-5963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15895771#comment-15895771
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ASF GitHub Bot commented on FLINK-5963:
---------------------------------------
Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/3472#discussion_r104292001
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/aggregate/DataSetPreAggFunction.scala
---
@@ -0,0 +1,87 @@
+/*
+ * 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.lang.Iterable
+
+import org.apache.flink.api.common.functions._
+import org.apache.flink.configuration.Configuration
+import org.apache.flink.table.functions.{Accumulator, AggregateFunction}
+import org.apache.flink.types.Row
+import org.apache.flink.util.{Collector, Preconditions}
+
+/**
+ * [[GroupCombineFunction]] and [[MapPartitionFunction]] to compute
pre-aggregates for batch
+ * (DataSet) queries.
+ *
+ * @param aggregates The aggregate functions.
+ * @param aggInFields The positions of the aggregation input fields.
+ * @param groupingKeys The positions of the grouping keys in the input.
+ */
+class DataSetPreAggFunction(
+ private val aggregates: Array[AggregateFunction[_ <: Any]],
+ private val aggInFields: Array[Int],
+ private val groupingKeys: Array[Int])
+ extends AbstractRichFunction
+ with GroupCombineFunction[Row, Row]
--- End diff --
Can we align with and extend?
The suggestion just ref to: [Scalar Class/Object/Trait constructors
declarations ](http://docs.scala-lang.org/style/declarations)
> Remove preparation mapper of DataSetAggregate
> ---------------------------------------------
>
> Key: FLINK-5963
> URL: https://issues.apache.org/jira/browse/FLINK-5963
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Affects Versions: 1.3.0
> Reporter: Fabian Hueske
> Assignee: Fabian Hueske
> Priority: Minor
>
> With the new UDAGG interface we do not need the preparation mapper anymore.
> It adds overhead because
> - it is another operator
> - it prevents to use {{AggregateFunction.accumulate()}} in a combiner or
> reducer.
> Hence, it should be removed.
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