AWT Usage while session in RESPONSE state


AWT Usage while session in RESPONSE state


One of my session is in RESPONSE state for more than 12hrs while trying to export 1.2 billion rows, 53.5GB size. Like to know whether AWT will be in use by the session or released?

Also, what I knew BYNET (merge) buffer hold data and release the AWT's when session get into response state. But what amount of data/size BYNET buffer can hold? what is the size of BYNET buffer?

Appreciate your inputs on this.

Best Regards,

Velu N

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Re: AWT Usage while session in RESPONSE state


What version of Teradata do you have?

AFAIK, you can't see AWT utilization by session level. Only AMP and Performance Group (Workload).




Re: AWT Usage while session in RESPONSE state

Hi Velu

Sessions in responding mode doesn't hold up AWT. AWTs are ionvolved when AMPS are in active state, once AMP became idle it won't use AWTs. But when response was sent to dispatcher from AMP, BYNET may use one AWT.AWTs doing work on behalf of a query are released at the end of the final query step before the BYNET merge process begins, even when there is a large answer set to return.The last AMP to complete its work in building a query’s final spool collects row counts from all AMPs, responds to the dispatcher that the step is complete and reports the final row count. The dispatcher then tells the BYNET to start a merge process. The BYNET driver has special data buffers where the rows that will be used to feed into the merge must be placed. AWTs are acquired, as needed, only for the brief period of time it takes to move data from the final spool file into the BYNET buffersreleased.AMP worker tasks being used during BYNET merge processing will have the highest work type, WorkControl, and will be running at the maximum priority, the System Performance Group (Allocation Group 200). Something you should keep an eye on.