mcstock wrote:
>if we do an apples to apples, with the developer testing with a realistic
>data set and test environment -- i'd still give a lot more then 0.1% margin
>of error to the CBO. what i've think you may have identified is the CBO
>becoming a better safety net for developers that don't (or can't) test
>adaquately
>
>--- mcs
>
>"Daniel Morgan" <damorgan_at_x.washington.edu> wrote in message
>news:1066949637.846158_at_yasure...
>
>
>>mcstock wrote:
>>
>>
>>
>>>never say never
>>>
>>>as the CBO improves, hints may be needed less
>>>
>>>however we can never say that the CBO will always be smarter than the
>>>developer (or that the CBO developers will always be smarter than the
>>>application developers)
>>>
>>>----------------------------------------
>>>Mark C. Stock
>>>www.enquery.com
>>>(888) 512-2048
>>>
>>>
>>>
>>>
>>True. But I'd venture that 99.9+% of the time the CBO is smarter than
>>the developer that
>>developers on a DEV instance with a bit of sample data and a few users,
>>and then moves
>>the application into TEST with six month old clone of a subset of
>>production data and a
>>dozen users, at most, that then gets moved into the full PROD instance
>>with 1000 users
>>beating it up full-time 7x24.
>>
>>--
>>Daniel Morgan
>>http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp
>>http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp
>>damorgan_at_x.washington.edu
>>(replace 'x' with a 'u' to reply)
>>
>>
>>
My point is that even developers that do EXPLAIN PLAN and TKPROF, keep
statistics current
with DBMS_STATS, and have used DBMS_PROFILER to thoroughly work-over
their code
are still unable to exercise any control over how that code will run in
production. Different data,
with different volumes and cardindality, on different hardware, with
different operating system
and Oracle patch levels may do very different things. I'll put my trust
in the CBO the vast majority
of the time. Too many DBAs see their job as baby-sitting the backup and
recovery process.
--
Daniel Morgan
http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp
http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp
damorgan_at_x.washington.edu
(replace 'x' with a 'u' to reply)
Received on Fri Oct 24 2003 - 00:18:25 CDT
