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https://issues.apache.org/jira/browse/DRILL-350?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jacques Nadeau updated DRILL-350:
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Fix Version/s: Future
> Streaming Aggregate physical operator projects columns that may not be needed
> -----------------------------------------------------------------------------
>
> Key: DRILL-350
> URL: https://issues.apache.org/jira/browse/DRILL-350
> Project: Apache Drill
> Issue Type: Bug
> Reporter: Aman Sinha
> Fix For: Future
>
>
> A query may have GROUP-BY keys that are not part of the SELECT list.. for
> example: SELECT SUM(c1) FROM t1 GROUP BY a1, b1.
> The Streaming Aggregate physical operator currently projects all GROUP-BY
> columns with the assumption that a subsequent Project will drop the
> unnecessary columns. This is sub-optimal because we incur the memory and cpu
> overhead of populating the output record batch value vectors for those
> columns. Ideally, the operator could keep track of the columns that are
> needed by the parent (downstream) operator and only project those group-by
> columns.
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