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https://issues.apache.org/jira/browse/IMPALA-6088?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Ho updated IMPALA-6088:
-------------------------------
    Parent Issue: IMPALA-7301  (was: IMPALA-5865)

> Rack aware broadcast operator
> -----------------------------
>
>                 Key: IMPALA-6088
>                 URL: https://issues.apache.org/jira/browse/IMPALA-6088
>             Project: IMPALA
>          Issue Type: Sub-task
>          Components: Distributed Exec
>            Reporter: Mostafa Mokhtar
>            Priority: Major
>
> When conducting large scale experiments on a 6 rack cluster with aggregator 
> core network topology overall cluster bandwidth utilization was limited. 
> With aggregator core networks nodes and racks are not equidistant, which 
> means a broadcast operation can be inefficient as the broadcasting node needs 
> to send the same data N times to each node on a remote rack. 
> Ideally Rowbatches should be sent once per remote rack then a node on each 
> remote rack would broadcast within its rack. 
> Table below represent rack to rack latency for the 90% of operations, ration 
> between best and worst case is 7.3x 
> | ||  va||    vc||    vd1||   vd3||   ve|
> |va|  4,238|  4,290|  9,692|  8,897|  8,208|
> |vc|  9,290|  4,396|  30,952| 13,529| 14,578|
> |vd1| 9,131|  29,066| 4,346|  17,265| 16,849|
> |vd3| 7,409|  15,517| 17,265| 4,370|  4,687|
> |ve|  4,914|  16,894| 16,430| 4,713|  4,472|



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