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https://issues.apache.org/jira/browse/SPARK-35141?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenchen Fan reassigned SPARK-35141:
-----------------------------------
Assignee: Cheng Su
> Support two level map for final hash aggregation
> ------------------------------------------------
>
> Key: SPARK-35141
> URL: https://issues.apache.org/jira/browse/SPARK-35141
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.2.0
> Reporter: Cheng Su
> Assignee: Cheng Su
> Priority: Minor
>
> For partial hash aggregation (code-gen path), we have two level of hash map
> for aggregation. First level is from `RowBasedHashMapGenerator`, which is
> computation faster compared to the second level from
> `UnsafeFixedWidthAggregationMap`. The introducing of two level hash map can
> help improve CPU performance of query as the first level hash map normally
> fits in hardware cache and has cheaper hash function for key lookup.
> For final hash aggregation, we can also support two level of hash map, to
> improve query performance further.
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