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Posted to issues-all@impala.apache.org by "Tim Armstrong (JIRA)" <ji...@apache.org> on 2019/04/25 00:23:00 UTC

[jira] [Resolved] (IMPALA-7814) AggregationNode's memory estimate should be based on NDV only for non-grouping aggs

     [ https://issues.apache.org/jira/browse/IMPALA-7814?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tim Armstrong resolved IMPALA-7814.
-----------------------------------
    Resolution: Incomplete

I read this a couple of times and I don't understand exactly what the problem identified is. I dont' think we're likely to get to it soon so I'll just close.

> AggregationNode's memory estimate should be based on NDV only for non-grouping aggs 
> ------------------------------------------------------------------------------------
>
>                 Key: IMPALA-7814
>                 URL: https://issues.apache.org/jira/browse/IMPALA-7814
>             Project: IMPALA
>          Issue Type: Sub-task
>          Components: Frontend
>            Reporter: Pooja Nilangekar
>            Priority: Major
>              Labels: resource-management
>
> Currently, the AggregationNode always computes the NDV to estimate the number of rows. However, for grouping aggregates, the entire input has to be consumed before the output can be produced, hence its memory estimate should not consider the NDV.  This is acceptable for non-grouping aggregates because it only need to store the value expression during the build phase, instead of the entire tuple. 



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