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Message Posted: Mon, 03 Dec 2001 @ 13:00:54 GMT

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Subj:   Re: Derived Tables and 3710 Error
From:   Claybourne Barrineau


I agree that a single, traditional query without derived tables cannot join more than 64 tables; however, I was able to join 72 tables together by joining 7 derived tables. Each derived table joined 9 tables together.

I think that the '!' math symbol is referred to as a 'Factorial' in the States...it has been a while since my last Math class.

Again, my primary concern is that this proposed change in the way the optimizer will treat derived tables could have some very adverse effects on existing code. In the case of my code, without a change of the MaxParseTreeSegs, I will receive an error (3710.) Even with an increase in the number of MaxParseTreeSegs, my query will take significantly longer (my guess is ~150%) to run because of the increase in time required during the optimization phase that builds the optimal join strategy (due to the optimizer building a join strategy for 35 tables instead of two separate strategies for a set of 15 and 20 tables.)

I do hope the 'swich' you referred to is implemented if Teradata decides to change the way it currently treats derived table.


Claybourne Barrineau

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