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Message Posted: Fri, 30 Jul 2004 @ 20:34:19 GMT


     
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Subj:   Re: AMP Worker Tasks and Skewed Queries
 
From:   Ballinger, Carrie

Hi Robert,

Good observation...With row redistribution steps, and duplication steps as well, there will be one sender and one receiver awt on each AMP. Most sender tasks will free up their awt as soon as they complete their sending work. Immediately. A few sender tasks, even though they are finished with their work, are not able to be freed immediately due to some internal coordination that is part of Teradata's redistribution scheme, but the vast majority will be.

Receiver tasks are dependent on all sender tasks having completed, and secondly on completing their own backlog of work. When those two conditions exist on an AMP, a receiver task is also freed up, all but the last-done receiver, who has the additional work of telling the dispatcher the step is complete.


Thanks, --Carrie



     
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