kasakrisz opened a new pull request #1734:
URL: https://github.com/apache/hive/pull/1734


   ### What changes were proposed in this pull request?
   Introduce a new HiveConf setting to set lower bound of hash aggregation 
reduction. The default value is 0.5.
   During query compilation hash aggregation reduction is adjusted by 
calculating its effectiveness.
   With this patch if the adjusted reduction value is less than the configured 
lower bound the lower bound value will be used.
   
   ### Why are the changes needed?
   Some cases we end up with 0 values forcing the Group by operator to skip 
Hash aggregates and chooses streaming mode.
   
   ### Does this PR introduce _any_ user-facing change?
   No.
   
   ### How was this patch tested?
   


----------------------------------------------------------------
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.

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