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Posted to issues@tez.apache.org by "Zhiyuan Yang (JIRA)" <ji...@apache.org> on 2016/04/26 01:16:12 UTC
[jira] [Assigned] (TEZ-2104) A CrossProductEdge which produces
synthetic cross-product parallelism
[ https://issues.apache.org/jira/browse/TEZ-2104?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Zhiyuan Yang reassigned TEZ-2104:
---------------------------------
Assignee: Zhiyuan Yang
> 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
> Assignee: Zhiyuan Yang
> 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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