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https://issues.apache.org/jira/browse/TEZ-145?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487627#comment-14487627
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Tsuyoshi Ozawa commented on TEZ-145:
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[~gopalv] thanks for taking a look at my patch and your comment!
{quote}
but the edge connectivity is still shuffle + total-order merged for both edges
{quote}
You're right. We can use UnorderedPartitionedKVEdge for optimization since
aggregation tasks don't need sorting as you know.
{quote}
I will write a more detailed design document tomorrow and upload it here which
will expand on Bikas's earlier comment and I will draw out the runtime
expansion graphs to indicate the sort-preserving combiner instead of re-sorting
data along the way (since the combiner never mutates the keys or output
ordering).
{quote}
OK, Looking forward.
> Support a combiner processor that can run non-local to map/reduce nodes
> -----------------------------------------------------------------------
>
> Key: TEZ-145
> URL: https://issues.apache.org/jira/browse/TEZ-145
> Project: Apache Tez
> Issue Type: Bug
> Reporter: Hitesh Shah
> Assignee: Tsuyoshi Ozawa
> Attachments: TEZ-145.2.patch, WIP-TEZ-145-001.patch
>
>
> For aggregate operators that can benefit by running in multi-level trees,
> support of being able to run a combiner in a non-local mode would allow
> performance efficiencies to be gained by running a combiner at a rack-level.
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