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https://issues.apache.org/jira/browse/FLINK-15249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16998845#comment-16998845
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Chongchen Chen commented on FLINK-15249:
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the set union operation is O(N) -> O(1), but set union is only a part of
calculation. that's why it's not O(N) -> O(1) improvement in total. Disjoint
Set Data Structure has very good theoretical guarantee, it can be applied to
any kinds of topologies.
'Did you check why it becomes faster?'. For Disjoint Set Data Structure, set
union only need to set a key value in hashmap, but normal set operation need to
copy all elements from one set into another set.
> Improve PipelinedRegions calculation with Union Set
> ---------------------------------------------------
>
> Key: FLINK-15249
> URL: https://issues.apache.org/jira/browse/FLINK-15249
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Coordination
> Reporter: Chongchen Chen
> Priority: Major
> Labels: pull-request-available
> Attachments: PipelinedRegionComputeUtil.diff
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Union Set's Merge Set cost is O(1). current implementation is O(N). the
> attachment is patch.
> [Disjoint Set Data
> Structure|[https://en.wikipedia.org/wiki/Disjoint-set_data_structure]]
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