[jira] [Commented] (PIG-4587) Applying isFirstReduceOfKey for Skewed left outer join skips records

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

    [ https://issues.apache.org/jira/browse/PIG-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15105732#comment-15105732 ] 

Daniel Dai commented on PIG-4587:
---------------------------------

+1

> Applying isFirstReduceOfKey for Skewed left outer join skips records
> --------------------------------------------------------------------
>
>                 Key: PIG-4587
>                 URL: https://issues.apache.org/jira/browse/PIG-4587
>             Project: Pig
>          Issue Type: Bug
>    Affects Versions: 0.15.0
>            Reporter: Rohini Palaniswamy
>            Assignee: Daniel Dai
>            Priority: Critical
>             Fix For: 0.16.0
>
>         Attachments: PIG-4587-1.patch
>
>
> PIG-4377 introduced isFirstReduceOfKey to avoid extra records in case of over sampling. But the issue can occur only in the case of right outer join. But it is added to the plan in MRCompiler and TezCompiler (PIG-4580) for both left and right outer joins. We need to remove that extra check for right outer join. It is unnecessary performance penalty.



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