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https://issues.apache.org/jira/browse/HIVE-12882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15102636#comment-15102636
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Pengcheng Xiong commented on HIVE-12882:
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Why RCFile needs all 3 modes? This is something that I do not understand. :)
They achieve the same purpose and noscan obviously outperforms the other two
without any down side. Then why we need to keep partialscan and fullscan modes?
Thanks.
> Automatically choose to use noscan for stats collection
> -------------------------------------------------------
>
> Key: HIVE-12882
> URL: https://issues.apache.org/jira/browse/HIVE-12882
> Project: Hive
> Issue Type: Sub-task
> Reporter: Pengcheng Xiong
>
> noscan is leveraging the file system to derive the #rows and rawDataSize.
> According to [~ashutoshc], it now only works with RC and ORC file type. We
> would like Hive to automatically choose to use noscan or scan based on the
> file system when stats task starts or when user issues the same query
> "Analyze ...."
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