[jira] [Updated] (HIVE-15683) Measure performance impact on group by by HIVE-15580

["Xuefu Zhang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-15683?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Xuefu Zhang updated HIVE-15683:
-------------------------------
    Attachment: HIVE-15683.patch

Patch brought back the old implementation and provide a configuration to switch on the new implementation.

> Measure performance impact on group by by HIVE-15580
> ----------------------------------------------------
>
>                 Key: HIVE-15683
>                 URL: https://issues.apache.org/jira/browse/HIVE-15683
>             Project: Hive
>          Issue Type: Improvement
>          Components: Spark
>    Affects Versions: 2.2.0
>            Reporter: Xuefu Zhang
>            Assignee: Xuefu Zhang
>         Attachments: HIVE-15683.patch
>
>
> HIVE-15580 changed the way the data is shuffled for order by: instead of using Spark's groupByKey to shuffle data, Hive on Spark now uses repartitionAndSortWithinPartitions(), which generates (key, value) pairs instead of original (key, value iterator). This might have some performance implications, but it's needed to get rid of unbound memory usage by {{groupByKey}}.
> Here we'd like to compare group by performance with or w/o HIVE-15580. If the impact is significant, we can provide a configuration that allows user to switch back to the original way of shuffling.
> This work should be ideally done after HIVE-15682 as the optimization there should help the performance here as well. 



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