[jira] [Resolved] (SPARK-29831) Scan Hive partitioned table should not dramatically increase data parallelism

["L. C. Hsieh (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-29831?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

L. C. Hsieh resolved SPARK-29831.
---------------------------------
    Resolution: Won't Fix

> Scan Hive partitioned table should not dramatically increase data parallelism
> -----------------------------------------------------------------------------
>
>                 Key: SPARK-29831
>                 URL: https://issues.apache.org/jira/browse/SPARK-29831
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.0.0
>            Reporter: L. C. Hsieh
>            Assignee: L. C. Hsieh
>            Priority: Major
>
> Hive table scan operator reads each Hive partition as a HadoopRDD and unions all RDDs. The data parallelism of the result RDD can be dramatically increased, when reading a lot of partitions with a lot of files.
> Although users can also do coalesce by themselves, this ticket proposes to add a config to limit the maximum of the data parallelism. Because:
> 1. end-users might not understand details and get confused by big partition number. end-users might not know why/when/where to add coalesce.
> 2. users need to add coalesce to each time Hive table scan. It is annoying.



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