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From "Rui Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-19671) Distribute by rand() can lead to data inconsistency
Date Mon, 25 Jun 2018 02:48:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-19671?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16521790#comment-16521790
] 

Rui Li commented on HIVE-19671:
-------------------------------

We can check all RS and look for non-deterministic UDF in partition keys -- {{FunctionRegistry::isDeterministic}}
can be used.
I noted Hive itself may also use non-deterministic partitioning, e.g. to handle skewed GBY,
we first shuffle randomly to do partial aggregation. Do you think it makes sense to print
a warning for that?

> Distribute by rand() can lead to data inconsistency
> ---------------------------------------------------
>
>                 Key: HIVE-19671
>                 URL: https://issues.apache.org/jira/browse/HIVE-19671
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Rui Li
>            Assignee: Rui Li
>            Priority: Major
>
> Noticed the following queries can give different results:
> {code}
> select count(*) from tbl;
> select count(*) from (select * from tbl distribute by rand()) a;
> {code}



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