[jira] [Commented] (TEZ-2104) A CrossProductEdge which produces synthetic cross-product parallelism

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

    [ https://issues.apache.org/jira/browse/TEZ-2104?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15250780#comment-15250780 ] 

Zhiyuan Yang commented on TEZ-2104:
-----------------------------------

I'm going to take this one if there is no one else working on it.

> A CrossProductEdge which produces synthetic cross-product parallelism
> ---------------------------------------------------------------------
>
>                 Key: TEZ-2104
>                 URL: https://issues.apache.org/jira/browse/TEZ-2104
>             Project: Apache Tez
>          Issue Type: New Feature
>            Reporter: Gopal V
>              Labels: gsoc, gsoc2015, hadoop, hive, java, tez
>
> Instead of producing duplicate data for the synthetic cross-product, to fit into partitions, the amount of net IO can be vastly reduced by a special purpose cross-product data movement edge.
> The Shuffle edge routes each partition's output to a single reducer, while the cross-product edge routes it into a matrix of reducers without actually duplicating the disk data.
> A partitioning scheme with 3 partitions on the lhs and rhs of a join operation can be routed into 9 reducers by performing a cross-product similar to 
> (1,2,3) x (a,b,c) = [(1,a), (1,b), (1,c), (2,a), (2,b) ...]
> This turns a single task cross-product model into a distributed cross product.



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