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Posted to issues@spark.apache.org by "Apache Spark (Jira)" <ji...@apache.org> on 2021/01/26 06:48:00 UTC
[jira] [Assigned] (SPARK-34237) Add more metrics (fallback, spill)
for object hash aggregate
[ https://issues.apache.org/jira/browse/SPARK-34237?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Apache Spark reassigned SPARK-34237:
------------------------------------
Assignee: (was: Apache Spark)
> Add more metrics (fallback, spill) for object hash aggregate
> ------------------------------------------------------------
>
> Key: SPARK-34237
> URL: https://issues.apache.org/jira/browse/SPARK-34237
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.2.0
> Reporter: Cheng Su
> Priority: Trivial
>
> As object hash aggregate fallback mechanism is special - it will fallback to sort-based aggregation based on number of keys seen so far [0]. This fallback logic sometimes is sub-optimal and leads to unnecessary sort, and performance degradation in run-time. The first step to help user/developer debug is to add more related metrics on UI, e.g. spill size, and number of fallback to sort-based aggregation. (spill size metrics was already added for hash aggregate [1])
>
> [0]: [https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/ObjectAggregationIterator.scala#L161]
> [1]: [https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/HashAggregateExec.scala#L68]
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