[jira] [Commented] (TEZ-2103) Implement a Partial completion VertexManagerPlugin

["Alok Asok (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-2103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14366481#comment-14366481 ] 

Alok Asok commented on TEZ-2103:
--------------------------------

Hi,
I am a very keen to understand and work on Tez. I have gone through few technical papers and tez documentation in this regard. It would be very helpful to clearly understand the use-case of the task if somebody can give me a clearer understanding of the vertex manager plugin.

Thanks

> Implement a Partial completion VertexManagerPlugin
> --------------------------------------------------
>
>                 Key: TEZ-2103
>                 URL: https://issues.apache.org/jira/browse/TEZ-2103
>             Project: Apache Tez
>          Issue Type: New Feature
>            Reporter: Gopal V
>              Labels: gsoc, gsoc2015, hadoop, java, tez
>
> Currently, there is no sibling communication between tasks - this implies that a task can be completed by the first vertex in a wave of tasks, but the entire wave of tasks has to complete before success can be reported.
> This occurs in limit + filter query patterns common between the data access engines.
> {code}
> select * from data where x > 1 limit 10;
> {code}
> will run through a full-table scan worth of tasks to generate 10 rows per task, to aggregate it to produce the final 10 row result.
> The VertexManager receives counters/events early enough to short-circuit the rest of the vertex tasks, to prevent the remainder of tasks from getting scheduled when the limit condition has been satisfied by an initial sub-set of the tasks.
> This is a specialization of the VertexManagerPlugin for this common case scheduling pattern.



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