Re: Rule Based Optimization Going Away?

In article <RtYn9.8605$34.1015738_at_newsfeed.slurp.net>, Ender says...
>
>Howard J. Rogers wrote:
>
>>
>> "Peter Kellner" <pkellner_at_seventythirdstreet.com> wrote in message
>> news:ccec98ba.0210021655.32903b35_at_posting.google.com...
>>> I just was told by an Oracle Consultant that Oracle is planning on
>>> obsoleting rule based optimization and that in the future sometime,
>>> everyone will have to use cost based. Could this be true?
>>
>> Yup. There's a public document admitting as much on Metalink.
>>
>>>I have
>>> always used rule based when I know the distribution of the data pretty
>>> well ahead of time and can be smarter than the cost optimizer.
>>>
>>
>> Then you need to get with the rhythm and realise that the Opimizer has got
>> a whole lot more smarter than you're giving it credit for. So when was the
>> last time you could predict, with the rule based optimizer, what would be
>> in Index leaf nodes before you actually got to read them??? Huh??
>>
>> Seriously: there is no way you can beat the optimizer these days. And if
>> you say you can, I don't believe you.
>>
>> Anyway, whether I believe you or not: by 10i, the rule-based optimizer is
>> finished. So even if you are the God's gift to predicting access paths,
>> tough luck: Oracle won't support you.
>>
>>> Any official Oracle Info on this would be appreciated.
>>>
>>
>> You don't need any more "official" info than is readily available from
>> Metalink. The Rule Based Optimizer is DEAD and you need to upgrade. It's
>> not
>> a particular pain: the CBO is good these days. But you need to stop
>> wearing the flared jeans and oversized-lapels, and get with the groove.
>> Man.
>>
>> Regards
>> HJR
>>
>>
>>> -Peter Kellner
>
>What if I don't analyze the tables, will it force me to analyze the tables ?
>If no then CBO would have to revert back to RBO anyway.

It'll probably drop down to dynamic sampling

http://technet.oracle.com/docs/products/oracle9i/doc_library/release2/server.920/a96533/sql_1016.htm#26070

or use the default "sizes" it comes up with for the objects (sort of like rule but not like rule since there are many external influences on the CBO that the RBO just ignores like sort areas, size of sga, multi-block read count, etc etc etc)

--
Thomas Kyte (tkyte@oracle.com)             http://asktom.oracle.com/ 
Expert one on one Oracle, programming techniques and solutions for Oracle.
http://www.amazon.com/exec/obidos/ASIN/1861004826/  
Opinions are mine and do not necessarily reflect those of Oracle Corp