alamb commented on issue #7095:
URL: https://github.com/apache/datafusion/issues/7095#issuecomment-2539506517

   > I don't think there is a 'trivial' way to outperform HashBrown. I suspect 
that any performance improvements they achieved are due to factors other than 
having a better hashing mechanism than HashBrown
   
   Vectorizing the hash calculation is the big one, and DataFusion already do 
that
   
   There are more "exotic" hash table strategies that supposedly are able to 
vectorize the lookup / collision comparisons too (e.g. look up multiple keys in 
one instruction). The umbra papers talk about this, but that codebase is not 
open source and I am not sure how much it really improves performance in 
practice
   


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