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https://issues.apache.org/jira/browse/FLINK-26004?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhu Zhu reassigned FLINK-26004:
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Assignee: Lijie Wang
> Introduce ForwardForConsecutiveHashPartitioner
> ----------------------------------------------
>
> Key: FLINK-26004
> URL: https://issues.apache.org/jira/browse/FLINK-26004
> Project: Flink
> Issue Type: Sub-task
> Reporter: Lijie Wang
> Assignee: Lijie Wang
> Priority: Major
> Labels: pull-request-available
>
> If there are multiple consecutive and the same hash shuffles, SQL planner
> will change them except the first one to use forward partitioner, so that
> these operators can be chained to reduce unnecessary shuffles.
> However, sometimes the consecutive hash operators are not chained (e.g.
> multiple inputs), and this kind of forward partitioners will turn into
> forward job edges. These forward edges still have the consecutive hash
> assumption, so that they cannot be changed into rescale/rebalance edges,
> otherwise it can lead to incorrect results. This prevents the adaptive batch
> scheduler from determining parallelism for other forward edge downstream job
> vertices (see FLINK-25046).
> To solve it, I propose to introduce a new
> {{{}ForwardForConsecutiveHashPartitioner}}. When SQL planner optimizes the
> case of multiple consecutive the same groupBy, it should use the proposed
> partitioner, so that the runtime framework can further decide whether the
> partitioner can be changed to hash or not.
> h4.
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