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https://issues.apache.org/jira/browse/FLINK-4937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15661171#comment-15661171
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ASF GitHub Bot commented on FLINK-4937:
---------------------------------------
Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/2792#discussion_r87707250
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/runtime/aggregate/IncrementalAggregateAllTimeWindowFunction.scala
---
@@ -0,0 +1,62 @@
+/*
+ * 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.api.table.runtime.aggregate
+
+import java.lang.Iterable
+
+import org.apache.flink.api.table.Row
+import org.apache.flink.configuration.Configuration
+import org.apache.flink.streaming.api.windowing.windows.{TimeWindow,
Window}
+import org.apache.flink.util.Collector
+/**
+ * It Evaluate final aggregate value.
+ *
+ * @param aggregates The aggregate functions.
+ * @param groupKeysMapping The index mapping of group keys between
intermediate aggregate Row
+ * and output Row.
+ * @param aggregateMapping The index mapping between aggregate function
list and aggregated value
+ * index in output Row.
+ */
+class IncrementalAggregateAllTimeWindowFunction(
+ private val aggregates: Array[Aggregate[_ <: Any]],
+ private val groupKeysMapping: Array[(Int, Int)],
+ private val aggregateMapping: Array[(Int, Int)],
+ private val finalRowArity: Int,
+ private val windowStartPos: Option[Int],
+ private val windowEndPos: Option[Int])
+ extends
IncrementalAggregateAllWindowFunction[TimeWindow](aggregates,
--- End diff --
minor, indent
> Add incremental group window aggregation for streaming Table API
> ----------------------------------------------------------------
>
> Key: FLINK-4937
> URL: https://issues.apache.org/jira/browse/FLINK-4937
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Affects Versions: 1.2.0
> Reporter: Fabian Hueske
> Assignee: sunjincheng
>
> Group-window aggregates for streaming tables are currently not done in an
> incremental fashion. This means that the window collects all records and
> performs the aggregation when the window is closed instead of eagerly
> updating a partial aggregate for every added record. Since records are
> buffered, non-incremental aggregation requires more storage space than
> incremental aggregation.
> The DataStream API which is used under the hood of the streaming Table API
> features [incremental
> aggregation|https://ci.apache.org/projects/flink/flink-docs-release-1.2/dev/windows.html#windowfunction-with-incremental-aggregation]
> using a {{ReduceFunction}}.
> We should add support for incremental aggregation in group-windows.
> This is a follow-up task of FLINK-4691.
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