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https://issues.apache.org/jira/browse/IMPALA-5032?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tim Armstrong resolved IMPALA-5032.
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Resolution: Later
Doesn't seem to have been a problem.
> Consider user controls for sort materialization
> -----------------------------------------------
>
> Key: IMPALA-5032
> URL: https://issues.apache.org/jira/browse/IMPALA-5032
> Project: IMPALA
> Issue Type: Improvement
> Components: Clients
> Affects Versions: Impala 2.10.0
> Reporter: Thomas Tauber-Marshall
> Priority: Major
> Labels: performance
>
> A change currently being worked on
> (https://issues.cloudera.org/browse/IMPALA-4731) is introducing cost-based
> materialization of sorting exprs. This has the potential to introduce
> regressions if we make a bad decision, so it might be nice if the user had a
> way of overriding this decision.
> There are some questions to consider here:
> - Should we provide a query option, hint, or both?
> - Should a potential hint apply to the whole "order by" list or to each sort
> expr individually?
> - Should we allow the hint to override our decision when its either pointless
> (eg. forcing materialization of SlotRefs) or dangerous (eg. forcing
> non-materialization of potentially non-deterministic exprs)?
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