Xuefu Zhang created HIVE-15683:
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Summary: 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
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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