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Message Posted: Mon, 04 Apr 2005 @ 14:50:11 GMT
I need some help on what is going on in the OLAP functions.
Every time I use an OLAP function I get a step in the explain like:
8) We do an all-AMPs STAT FUNCTION step from Spool 2 (Last Use) by way of an all-rows scan into Spool 9 (Last Use), which is assumed to be redistributed by value to all AMPs. The result rows are put into Spool 1 (group_amps), which is built locally on the AMPs.
What is going on here? Why the two spool files? From (2) over (9) into (1)? And what really, really confuses me is the phrase:
"which is assumed to be redistributed "
Assumed to be redistributed? Assumed? Or Redistributed?
I have looked through the doku for anything providing more info on this, but I can't find anything.
ANY knowledgable input on this would be highly appreciated!!!
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