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Date: Tue, 3 Nov 2009 19:34:32 +0000 (UTC)
From: "Zheng Shao (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Subject: [jira] Commented: (HIVE-549) Parallel Execution Mechanism
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    [ https://issues.apache.org/jira/browse/HIVE-549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12773142#action_12773142 ] 

Zheng Shao commented on HIVE-549:
---------------------------------

Agree. We should have "taskId()/totalTasks" in the job name.

> 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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