Gopal V created TEZ-2104:
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Summary: 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: Improvement
Reporter: Gopal V
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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