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https://issues.apache.org/jira/browse/SPARK-37001?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenchen Fan resolved SPARK-37001.
---------------------------------
Fix Version/s: 3.2.1
3.3.0
Resolution: Fixed
Issue resolved by pull request 34270
[https://github.com/apache/spark/pull/34270]
> Disable two level of map for final hash aggregation by default
> --------------------------------------------------------------
>
> Key: SPARK-37001
> URL: https://issues.apache.org/jira/browse/SPARK-37001
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.2.0, 3.3.0
> Reporter: Cheng Su
> Assignee: Cheng Su
> Priority: Minor
> Fix For: 3.3.0, 3.2.1
>
>
> This JIRA is to disable two level of maps for final hash aggregation by
> default. The feature was introduced in
> [#32242|https://github.com/apache/spark/pull/32242] and we found it can lead
> to query performance regression when the final aggregation gets rows with a
> lot of distinct keys. The 1st level hash map is full so a lot of rows will
> waste the 1st hash map lookup and inserted into 2nd hash map. This feature
> still benefits query with not so many distinct keys though, so introducing a
> config to allow query to enable the feature when seeing benefit.
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