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Message Posted: Wed, 01 Dec 2004 @ 17:04:05 GMT

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Amol,

Concerning the second of your questions (shown below), when rows are redistributed during join processing, there is a same-node optimization that is done by the message system. The redistribution message, when it is sent, uses vproc and node addressing rather than hash addressing (it could be a different node, different AMP, same node, different AMP, or same node, same AMP). The optimization consists of recognizing when the destination is on the same node as the sender, and routing that message to the correct AMP, without leaving the node. Only rows being redistributed off the node from which they were sent will be handed off to the BYNET. A row being being sent out and returned to the same AMP leaves the AMP within a sender task, and returns to the same AMP within a receiver task.

Thanks, -Carrie

------- the question ---------
I was curious to know that during redistributions of spool to different amps (Merge joins where Primary indices are different) there would be some records that would come to same amp after rehashing on the basis of join columns. Do they really go to the BYNET or message passing layer for rehashing or are these records never sent to BYNET and directly spooled locally.
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