RE: ORDER BY and first_rows_10 madness

  • From: "Milen Kulev" <makulev@xxxxxxx>
  • To: Brandon.Allen@xxxxxxxxxxx
  • Date: Mon, 18 Dec 2006 12:44:35 +0100

Hi Brandon, 
thank you for the hint
ML Note:272202.1 discussed Bug bug 4570598, related to FIRST_ROWS 
hint/optimizer mode.
FIRST_ROWS  is as far as know some kind of "hybrid" between RBO und CBO -> many 
heuristic rules are used, and that is why the cost calculations in this mode 
are not always driving the decisions of CBO.
Anyway, I have tried with 
"_sort_elimination_cost_ratio"  1, 10, 50,  even 100, but I am getting the same 
(suboptimal)  plan. 

Best Regards, Milen 
P.S. I further problem is that I can not use "_sort_elimination_cost_ratio" as 
hint (Oracle version is 9i, not 10G)

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