Re: Fed Up with being a DBA

Domenic G. wrote:

>Daniel,
>
>For your information, I am fully up-to-date with all the new Oracle
>features -- I don't need YOU to tell me to take a course. I was the
>first one to use Refresh On Commit Materialized Views, Locally Managed
>Tablespaces, Automatic Segment Space Management, pga_aggregate_target,
>etc. etc. etc.
>
>I've also been burned by the sheer amount of bugs in every new feature
>Oracle implements. If you were as experienced as you say you are, you
>would know that the COST based optimizer is FAR from perfect, and is
>geared more towards data warehousing applications and not OLTP -- OLTP
>is all about index scan index scan index scan -- GET IT? There is no
>need to continually evaluate the cost of doing index scans when your
>application is designed to retrieve <10 rows per transaction on
>indexed searches. Yes, I've used histograms with COST on skewed
>columns --- HAVE YOU dived in to that level of detail? Or are you one
>of those DBAs that stays at the 30,000 foot level and assumes all
>tuning comes from juggling the friggin init.ora parameters and looking
>at wait events, or partitioning tables to kingdom-come?
>
>Do you evaluate join order, predicate push down into subqueries when
>Oracle refuses to do it? Have you used stored outlines, or
>cursor_sharing to sub in bind variables for literals? I've used all
>those things. For OLTP, COST is counter-productive more often than
>not, and you can take that to the bank buddy. Then you change
>versions, and all your stable execution plans go right down the toilet
>-- so pull in the stored outlines to counteract the stupidity of the
>cost-based optimizer.
>
>When it comes to Oracle 9i, you can CLEAN MY SHOES buddy boy. Long
>live RBO.
>
>Domenic.
>
>
>
>Daniel Morgan <damorgan_at_x.washington.edu> wrote in message news:<1063376432.458094_at_yasure>...
>
>
>>Domenic G. wrote:
>>
>>
>>
>>>Daniel,
>>>
>>>You make some good points, but I'm not paid by the hour! DBCA is OK
>>>for beginners, but I like to use a script so that I can hit all the
>>>functionality. As for COST, of course it works great for
>>>function-based indexes, query rewrite, partitioning, bitmap-join
>>>indexes, but if I want a straight NL with index scans on the join keys
>>>with one index scan on the driving table, COST seems to outsmart
>>>itself more often than not. For skewed columns, it works great. The
>>>whole concept behind COST is to LEAN AWAY from indexes when you're
>>>joining entire tables. Still, RULE is useful is certain situations,
>>>and if Oracle decides to desupport it, I'll kill them. I was able to
>>>increase system performance on one DB 20 times by simply changing to
>>>RULE -- COST kept doing hash joins when only a few rows were selected
>>>and the column was indexed!!!
>>>
>>>Domenic.
>>>
>>>
>>>
>>>
>>Perhaps that's why that Oracle bus almost hit Larry yesterday. We can
>>laugh now but it wasn't that funny when it happened.
>>
>>But seriously ... RBO is already dead. Get over it. Personally I haven't
>>used RBO for several years and would be hard pressed to find a query
>>that worked better with RBO than with CBO provided a proper
>>understanding of CBO and how to tune for it.
>>
>>I wasn't just being ornry when I suggested you take a class ... I was
>>serious. No doubt you've been in Oracle quite a long time and likely are
>>still applying version 7.x and 8.0 lessons to 9i. That will stop being
>>an option about two minutes after you have 10g.
>>
>>Years after the release of 9i we still get posts here asking what
>>happened to server manager (svrmgrl). It is not to hard to imagine
>>ourselves three years from now fielding posts with questions such as "I
>>tried to build a rollback segment and ...." or my soon to be favorite
>>"how come I can't build a tablespace with the code I used in version X?"
>>Don't become dinosaur ... evolve. ;-)
>>
>>

Perhaps you should check out the links under my signature. Done them all and I've had 10g on my desktop for several months too. But what I'm going to tell you is not a violation of my NDA but from public material published by Oracle:

The RBO is dead! Get over it! ;-)

-- 
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)