[jira] [Issue Comment Deleted] (FLINK-3480) Add hash-based strategy for ReduceFunction

["Greg Hogan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-3480?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Greg Hogan updated FLINK-3480:
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    Comment: was deleted

(was: Today I bumped into the performance discrepancy where a forwarding ship strategy can hurt performance since we can only do a sorted reduce whereas with a partition hash we can use the new hash-combiner.

What would be the spilling strategy for a hash-reducer and would this look much different from using the hash-combiner followed by the sort-reducer?)

> Add hash-based strategy for ReduceFunction
> ------------------------------------------
>
>                 Key: FLINK-3480
>                 URL: https://issues.apache.org/jira/browse/FLINK-3480
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Local Runtime
>            Reporter: Fabian Hueske
>
> This issue is related to FLINK-3477. 
> While FLINK-3477 proposes to add hash-based combine strategy for ReduceFunction, this issue aims to add a hash-based strategy for the final aggregation.
> This will need again a special hash-table aggregation which allows for in-place updates and append updates. However, it also needs to support spilling to disk in case of too tight memory budgets.



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