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From "Chaitanya Mishra (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-549) Parallel Execution Mechanism
Date Tue, 03 Nov 2009 19:38:32 GMT

    [ https://issues.apache.org/jira/browse/HIVE-549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12773144#action_12773144
] 

Chaitanya Mishra commented on HIVE-549:
---------------------------------------

We are still printing total number of MR jobs.
However we are changing job names to taskid (i.e Stage-x) format instead of 3/5

I can switch back to 3/5 kind of format which depended on the curjobno variable , but the
issue there is that the order in which tasks are launched might change over runs, and therefore
the job name can change. 

Let me know which one sounds better.

> Parallel Execution Mechanism
> ----------------------------
>
>                 Key: HIVE-549
>                 URL: https://issues.apache.org/jira/browse/HIVE-549
>             Project: Hadoop Hive
>          Issue Type: Wish
>          Components: Query Processor
>            Reporter: Adam Kramer
>            Assignee: Chaitanya Mishra
>         Attachments: HIVE-549-v3.patch
>
>
> In a massively parallel database system, it would be awesome to also parallelize some
of the mapreduce phases that our data needs to go through.
> One example that just occurred to me is UNION ALL: when you union two SELECT statements,
effectively you could run those statements in parallel. There's no situation (that I can think
of, but I don't have a formal proof) in which the left statement would rely on the right statement,
or vice versa. So, they could be run at the same time...and perhaps they should be. Or, perhaps
there should be a way to make this happen...PARALLEL UNION ALL? PUNION ALL?

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