Re: Bitmap index costing - how to influence

  • From: Randolf Geist <info@xxxxxxxxxxxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Sun, 29 Mar 2009 14:02:35 +0200

> Why use undocumented OPT_PARAM  when INDEX_COMBINE is documented and
> provided?


thanks for making that point. I generally second that one shouldn't use 
undocumented parameters/features if possible. Unfortunately Oracle doesn't 
provide (yet) an officially documented way to influence parameters like OICA / 
OIC on statement level, that's why I suggested it in this particular case to 
limit the effects of this parameter as much as possible.

There are obviously many different possibilities how the index usage in this 
particular case could be hinted/forced, but the INDEX_COMBINE and the 
OPTIMIZER_INDEX_COST_ADJ suggestions provide quite different means, so it 
depends what the objective is in the particular situation.


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