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https://issues.apache.org/jira/browse/IMPALA-4625?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joe McDonnell closed IMPALA-4625.
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Resolution: Won't Do
> Parquet Row Group Size optimization
> -----------------------------------
>
> Key: IMPALA-4625
> URL: https://issues.apache.org/jira/browse/IMPALA-4625
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Affects Versions: Impala 2.2.4
> Reporter: Alan Choi
> Priority: Major
>
> For highly selective query, once we can narrow it down to a single Parquet
> file that matches the predicate, Impala still has to process that single
> file. Right now, a single Parquet file generated by Impala has only 1 row
> group and its default size is 256MB. A row group is processed in serial
> cannot be parallelized at this moment. Processing a 256MB row group can takes
> several sec, even for a very simple predicate. To improve the response time
> of such highly selective query, the row group must be smaller.
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