alamb commented on PR #21107:
URL: https://github.com/apache/datafusion/pull/21107#issuecomment-4118493733

   > Previously, order-preserving variants could be removed when 
prefer_existing_sort = false or when there was no explicit ordering 
requirement, even if dropping the ordering would force a parent operator such 
as AggregateExec to fall back to blocking execution.
   
   I am not sure this is a "bug" necessarily -- more like a tradeoff. I believe 
the enforce_distribution plan will attempt to increase plan parallelism even if 
it has to resort by default 
   
   My understanding is that this is what the prefer_existing_sort setting 
controls 
   ```
   prefer_existing_sort = false
   ```
   
   So if you want plans to keep existing sorts and not increase parallelism in 
that case, you should set `prefer_existing_sort = true` -- this is what we do 
in InfluxDB FWIW
   


-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: [email protected]

For queries about this service, please contact Infrastructure at:
[email protected]


---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]

Reply via email to