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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-4937) Add incremental group window aggregation for streaming Table API
Date Fri, 18 Nov 2016 14:30:59 GMT

    [ https://issues.apache.org/jira/browse/FLINK-4937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15676847#comment-15676847

ASF GitHub Bot commented on FLINK-4937:

Github user fhueske commented on a diff in the pull request:

    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/nodes/datastream/DataStreamAggregate.scala
    @@ -231,6 +297,64 @@ object DataStreamAggregate {
    +  private def createAllWindowIncrementalAggregationFunction(
    --- End diff --
    I think we can move all `create*Window*Function` methods (also the ones that have been
here before) to `AggregateUtil`. 

> 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
> The DataStream API which is used under the hood of the streaming Table API features [incremental
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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