Re: RBO changes plan from 8i to 9i

From: Alex Gorbachev <gorbyx_at_gmail.com>
Date: Wed, 12 Jul 2006 15:41:43 +0200
Message-ID: <c2213f680607120641g7671b3cbk29d858fc13264ab@mail.gmail.com>

2006/7/12, Sergey Popov <sspopov_at_gmail.com>:
> With CBO making much better decisions on execution plan...

Very optimistic statement. :-) CBO is supposed to make them better ON AVERAGE providing_certain_conditions_are_met.

Another thing where CBO is far from RBO (and I doubt it will be ever able to reach it) is execution plan stability. With RBO you are almost sure that you plans stay intact even if they are suboptimal. "Almost" becuase there are some minor issues like index creation order.

-- 
Best regards,
Alex Gorbachev

http://blog.oracloid.com
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Received on Wed Jul 12 2006 - 08:41:43 CDT