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https://issues.apache.org/jira/browse/IMPALA-7814?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pooja Nilangekar updated IMPALA-7814:
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Description: 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.
Summary: AggregationNode's memory estimate should be based on NDV only
for non-grouping aggs (was: Aggregation Node's memory estimate should be
based on NDV only for non-grouping aggs )
> 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
> Reporter: Pooja Nilangekar
> Priority: Major
>
> 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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