[jira] Commented: (PIG-1709) Skewed join use fewer reducer for extreme large key

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

    [ https://issues.apache.org/jira/browse/PIG-1709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12968872#action_12968872 ] 

Richard Ding commented on PIG-1709:
-----------------------------------

+1

> Skewed join use fewer reducer for extreme large key
> ---------------------------------------------------
>
>                 Key: PIG-1709
>                 URL: https://issues.apache.org/jira/browse/PIG-1709
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: 0.8.0
>            Reporter: Daniel Dai
>            Assignee: Daniel Dai
>             Fix For: 0.8.0
>
>         Attachments: PIG-1709-1.patch
>
>
> In skewed join, we use PartitionSkewedKeys to calculate number of reducers needed for a single key. If the result if larger than the number of total reducers, we will round it with reducer#. Eg, if Pig calculates that we need 12 reducers to hold a key in memory, and total reducers for this job is 10, we then allocate 2 reducers to this key; We shall use all 10 reducers in this case.

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