[jira] [Commented] (PIG-3562) Implement combiner optimizations for DISTINCT

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

    [ https://issues.apache.org/jira/browse/PIG-3562?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13864973#comment-13864973 ] 

Alex Bain commented on PIG-3562:
--------------------------------

ReviewBoard posted at https://reviews.apache.org/r/16717/

> Implement combiner optimizations for DISTINCT
> ---------------------------------------------
>
>                 Key: PIG-3562
>                 URL: https://issues.apache.org/jira/browse/PIG-3562
>             Project: Pig
>          Issue Type: Sub-task
>          Components: tez
>    Affects Versions: tez-branch
>            Reporter: Alex Bain
>            Assignee: Alex Bain
>             Fix For: tez-branch
>
>         Attachments: PIG-3562-0.patch
>
>
> Currently, DISTINCT is implemented in a straightforward manner per https://issues.apache.org/jira/browse/PIG-3538.
> However, we can implement two types of combiner optimizations for DISTINCT, just as the MRCompiler does for map-reduce:
> 1. A simple DistinctCombiner that throws away the duplicate tuples
> 2. An optimizer that transforms certain uses of DISTINCT into an algebraic udf form



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