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Posted to issues-all@impala.apache.org by "Tim Armstrong (Jira)" <ji...@apache.org> on 2019/09/16 22:51:00 UTC
[jira] [Updated] (IMPALA-988) Join strategy (broadcast vs shuffle)
decision does not take memory consumption and other joins into account
[ https://issues.apache.org/jira/browse/IMPALA-988?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Tim Armstrong updated IMPALA-988:
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Summary: Join strategy (broadcast vs shuffle) decision does not take memory consumption and other joins into account (was: Join strategy (broadcast vs shuffle) decision does not take mem limit and other joins into account)
> Join strategy (broadcast vs shuffle) decision does not take memory consumption and other joins into account
> -----------------------------------------------------------------------------------------------------------
>
> Key: IMPALA-988
> URL: https://issues.apache.org/jira/browse/IMPALA-988
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Affects Versions: Impala 1.2.1
> Reporter: Alan Choi
> Priority: Minor
> Labels: resource-management
>
> The amount of available memory changes the trade-off between partitioned and shuffle join strategies: if switching to shuffle join can avoid spilling to disk, it may be worth paying the cost of the additional network transfer.
> There are two issues:
> 1. Join strategy decision only takes query mem-limit into account but ignore process mem-limit.
> 2. Join strategy decision does not take other joins of the same query into account. When multiple joins are present, it'll go over the mem-limit.
> Note that when IMPALA-3200 is completed, this shouldn't prevent the query running to completion, but still affects performance.
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