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Posted to dev@pig.apache.org by "Cheolsoo Park (JIRA)" <ji...@apache.org> on 2014/09/02 03:51:21 UTC

[jira] [Issue Comment Deleted] (PIG-4148) Tez order-by is often skewed because FindQuantiles UDF is called with small number

     [ https://issues.apache.org/jira/browse/PIG-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Cheolsoo Park updated PIG-4148:
-------------------------------
    Comment: was deleted

(was: The patch changes the number of samples to parallelism x per-task sample size.)

> Tez order-by is often skewed because FindQuantiles UDF is called with small number
> ----------------------------------------------------------------------------------
>
>                 Key: PIG-4148
>                 URL: https://issues.apache.org/jira/browse/PIG-4148
>             Project: Pig
>          Issue Type: Sub-task
>          Components: tez
>            Reporter: Cheolsoo Park
>            Assignee: Cheolsoo Park
>             Fix For: 0.14.0
>
>
> In Tez, FindQuantiles UDF is called with a smaller number of samples than MR resulting in skew in range partitions.
> For example, I have a job that runs sampling with a parallelism of 300. Since each task samples 100 records, the total sample should be 30K. But FindQuantiles UDF is called with only 300 samples.



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