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Posted to issues@hive.apache.org by "Panagiotis Garefalakis (Jira)" <ji...@apache.org> on 2020/04/09 15:33:00 UTC

[jira] [Updated] (HIVE-23166) Guard VGB from flushing too often

     [ https://issues.apache.org/jira/browse/HIVE-23166?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Panagiotis Garefalakis updated HIVE-23166:
------------------------------------------
    Summary: Guard VGB from flushing too often  (was: Protect VGB from flushing too often)

> Guard VGB from flushing too often
> ---------------------------------
>
>                 Key: HIVE-23166
>                 URL: https://issues.apache.org/jira/browse/HIVE-23166
>             Project: Hive
>          Issue Type: Improvement
>          Components: llap
>    Affects Versions: 4.0.0
>            Reporter: Panagiotis Garefalakis
>            Assignee: Panagiotis Garefalakis
>            Priority: Major
>
> The existing flush logic in our VectorGroupByOperator is completely static.
>  It depends on the: number of HtEntries (*hive.vectorized.groupby.maxentries*) and the MAX memory threshold (by default 90% of available memory)
>  
> Assuming that we are not memory constrained the periodicity of flushing is currently dictated by the static number of entries (1M by default) which can be also misconfigured to a very low value.
> I am proposing along with maxHtEntries, to also take into account current memory usage, to avoid flushing too ofter as it can hurt op throughput for particular workloads.



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