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Archives of the TeradataForum
Message Posted: Wed, 14 Dec 2005 @ 10:44:11 GMT
| Subj: | | Re: NoDerivedStats |
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| From: | | Dieter Noeth |
David Clough wrote:
| | On a slightly different issue (although not altogether unrelated to the previous question), does anyone know what the "noderivedstats"
system setting does ? | |
| | I know how to set it on and off but nobody that I know seems to know precisely what it actually does as such. | |
This is one of the many undocumented diagnostic settings...
| | What I thought it might have something to do with is to dynamically allow the optimizer to change tack based up stats that it gathers
from Spool at time of execution, but I'd be guessing. | |
I don't know, but i think it deals with using stats from a base table for a join index, e.g. base table column x used in join index, but no
stats collected on join index column x.
Hint: this could be easily checked ;-)
Dieter
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