[jira] [Created] (SPARK-12125) pull out nondeterministic expressions from Join

["iward (JIRA)" <ji...@apache.org>]

iward created SPARK-12125:
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             Summary: pull out nondeterministic expressions from Join
                 Key: SPARK-12125
                 URL: https://issues.apache.org/jira/browse/SPARK-12125
             Project: Spark
          Issue Type: Bug
    Affects Versions: 1.5.2, 1.5.1, 1.5.0
            Reporter: iward


Currently,*nondeterministic expressions* are only allowed in *Project* or *Filter*,And only when we use nondeterministic expressions in *UnaryNode* can be pulled out.

But,Sometime in many case,we will use nondeterministic expressions to process *join keys* avoiding data skew.for example:
{noformat}
select * 
from tableA a 
join 
(select * from tableB) b 
on upper((case when (a.brand_code is null or a.brand_code = '' ) then cast( (-rand() * 10000000 ) as string ) else a.brand_code end ))  = b.brand_code

{noformat}

This PR introduce a mechanism to pull out nondeterministic expressions from *Join*,so we can use nondeterministic expression in *Join* appropriately.



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