Re: RBO to CBO

From: DA Morgan <damorgan_at_x.washington.edu>
Date: Fri, 31 Dec 2004 00:41:35 -0800
Message-ID: <41d50fa0$1_2@127.0.0.1>

Jack wrote:

> "DA Morgan" <damorgan_at_x.washington.edu> wrote in message
> news:41d44380$1_1_at_127.0.0.1...
>

>>Niall Litchfield wrote:
>>
>>
>>>"DA Morgan" <damorgan_at_x.washington.edu> wrote in message 
>>>news:41d3a2b3$1_2_at_127.0.0.1...
>>>
>>>
>>>>Oradba Linux wrote:
>>>>
>>>>
>>>>
>>>>>Any major/minor issues to watch out for during the conversion especially
>>>>>with regards to sql written specifically to RBO
>>>>
>>>>Strip out hints and retune each statement as required.
>>>
>>>
>>>I wouldn't regard sql with hints as 'written especially for the CBO', 
>>>since with the exception of the rule hint they would run under the CBO.
>>
>>Earlier this year I did a one-month gig with a local telecom. Moved
>>them from 8i RULE to 10g CBO. You'd likely be amazed how much of
>>their SQL was hinted ... heavily hinted: And the CBO didn't like any
>>of it.
>>-- 
>>Daniel A. Morgan
>>University of Washington
>>damorgan_at_x.washington.edu
>>(replace 'x' with 'u' to respond)

>
>
> Hi Daniel
>
> Was it 10g without any patches?
> There are some issues in CBO (9i/9iR2) f.ex with complex views.
> Does CBO work better in 10g than 9iR2 .
>
> Do you have experience with Heterogenous Services and External tables, what
> should be watch out (in CBO)?
>
> Jack

10g without patches and after the move the improvement in performance was dramatic. CBO in 10g is much improved.

Have not experienced any problems with Heterogenous Services or External Tables but that is not to say others haven't. Check metalink for any issues.

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)

Received on Fri Dec 31 2004 - 02:41:35 CST