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Posted to user@hive.apache.org by Abhishek <ab...@gmail.com> on 2012/09/27 19:40:57 UTC

Reduce phase initialization

Hi all,

In some of my hive scripts, reduce phase is not starting until map finishes 100%.What would be the reason for this.

Regards
Abhi


Sent from my iPhone

Re: Reduce phase initialization

Posted by Bertrand Dechoux <de...@gmail.com>.

Strictly speaking reduce can only start once all map is done. However copy
is part of the reported reduce metrics. So that's maybe why you are asking
the question. A simple answer is because you don't have much data so there
is only one mapper which means the copy will have to start after all (only
one) map finish.

Could you provide more information about your case? Like the metrics?

Regards

Bertrand

On Thu, Sep 27, 2012 at 7:40 PM, Abhishek <ab...@gmail.com> wrote:

> Hi all,
>
> In some of my hive scripts, reduce phase is not starting until map
> finishes 100%.What would be the reason for this.
>
> Regards
> Abhi
>
>
> Sent from my iPhone

-- 
Bertrand Dechoux