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Posted to github@arrow.apache.org by "mingmwang (via GitHub)" <gi...@apache.org> on 2023/06/14 06:58:06 UTC

[GitHub] [arrow-datafusion] mingmwang commented on issue #4973: Improve the performance of `Aggregator`, grouping, aggregaton

mingmwang commented on issue #4973:
URL: https://github.com/apache/arrow-datafusion/issues/4973#issuecomment-1590583787

   @alamb @ozankabak @yjshen @jiangzhx 
   
   For group by high cardinality columns, I will do some POC to support two levels of grouping state (PartitionedHashTable).
   The PartitionedHashTable approach was adopted by many other engines like ClickHouse, DuckDB and Databend. It is also mentioned in the "Morsel-Driven Parallelism" paper.  
   
   
   
   


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