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https://issues.apache.org/jira/browse/FLINK-4937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15661634#comment-15661634
]
ASF GitHub Bot commented on FLINK-4937:
---------------------------------------
Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/2792#discussion_r87714387
--- Diff:
flink-libraries/flink-table/src/test/scala/org/apache/flink/api/scala/stream/table/AggregationsITCase.scala
---
@@ -177,6 +177,58 @@ class AggregationsITCase extends
StreamingMultipleProgramsTestBase {
"Hi,1,1970-01-01 00:00:00.0,1970-01-01 00:00:00.01,1970-01-01
00:00:00.0")
assertEquals(expected.sorted, StreamITCase.testResults.sorted)
}
+
+ @Test
+ def testProcessingTimeSlidingGroupWindowOverCountWithAVG(): Unit = {
--- End diff --
thanks @wuchong ,Strongly Agree!
> 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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