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RE: Training for Oracle Performance tuning - Method-R is easy

From: Kerber, Andrew W. <Andrew.Kerber_at_umb.com>
Date: Fri, 28 Sep 2007 09:44:43 -0500
Message-ID: <D40740337A3B524FA81DB598D2D7EBB3097A8C4E@x6009a.umb.corp.umb.com> 





This is a useful method for a consultant.  However, if you are a full
time DBA for a single company, and are really interested in getting the
whole instance running well, tuning is an ongoing task that you will
never actually finish.



And I'm not saying it's not a good way to do things.  It's a highly
effective method for solving immediate problems, which is the reason
someone would hire a consultant.  Its just that different jobs have
different requirements.



-----Original Message-----


From: oracle-l-bounce_at_freelists.org


[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Ted Coyle
Sent: Friday, September 28, 2007 8:36 AM
To: fmhabash_at_gmail.com; sunil.kanderi_at_gmail.com
Cc: 'oracle-l'


Subject: RE: Training for Oracle Performance tuning - Method-R is easy



"This approach refuses to give any attention to instance level tuning. 
On some occasions, they won't even read a statspack report. " 



I just have to jump back in here.  I never read statspack reports.



I use Method-R to fix problems large and small every day.  I've posted a
real life example inline with the method.  In this case, I did make a
system


level change and I had no prior involvement with this client's system.



    
  
  1.   Select the top user actions for which the business needs improved
performance.  






----> System response time had grown worse over time.  One report in
particular used to take 15 minutes, but now took 2hrs.  This report
can't be


run in batch.  They really needed this particular report to run faster
since


it had to be kicked of by end users.



   2.  Collect properly scoped diagnostic data that will allow you to
identify the causes of response time consumption for each selected user
action while it is performing sub-optimally. 



 -----> In this case, we examined the xplans and key init settings

first.


It turns out they had skewed data and were biased toward table scans.  I
didn't trace, it wasn't necessary and as quoted from Jonathan Lewis,
"The


first (and only) rule of optimization is:  Avoid unnecessary effort."
We


tested based on changes to one setting to determine scope.



   3.  Execute the candidate optimization activity that will have the
greatest net payoff to the business. If even the best net-payoff
activity


produces insufficient net payoff, then suspend your performance
improvement


activities until something changes. 



 -----> the solution was to adjust optimizer_index_cost_adj.  The net

payoff


is that the report ran faster.  The subsequent test will be to see if
anything goes slower.  If so go to #4 otherwise were done.



Other options were suggested buy client resources, but all involved
substantial effort or code changes, none of which was going to happen.  



   4. Go to step 1.  ----> So far we're monitoring and all is well.




I didn't guess about the solution, but I did take a risk adjusting a
system


setting.  This risk turns out to be acceptable to the business because
it


solved their immediate problem and any subsequent issue can be resolved
quickly using this approach.  The problem was 4 months old by the time
it


landed in my cube.  I was able to determine the issue and suggest a
solution


in 4hrs.  It took 4 days to review and implement.  



Again, this was business focused.  I didn't need tracing to figure it
out,


this would be the next step if necessary, but I didn't need to go that
far


to make the report run faster.  



I don't know what's so hard about implementing Method-R; knowing what to
fix


once you know what is wrong is the hard part.  I provide the options and
let


the business decide.  I have a 100% success rate with Method-R and I
still


haven't made it 100% through any of my 100+ books.



-Ted



-----Original Message-----


From: oracle-l-bounce_at_freelists.org


[mailto:oracle-l-bounce_at_freelists.org]


On Behalf Of fmhabash


Sent: Wednesday, September 26, 2007 2:14 PM
To: sunil.kanderi_at_gmail.com


Cc: oracle-l


Subject: Re: Training for Oracle Performance tuning



I read the OraPub class description here 
http://resources.orapub.com/ProductDetails.asp?ProductCode=RPM&Show=Tech
Spec


s 


. My advice, take this class first then if you still need to, use the 
HotSos one. If you care to know why, keep reading ....



I have read and attended many Oracle perf approaches. Last one was 
HotSos Metho-R one. One thing that distinguishes HS from others is that 
they have a science-evidence-based approach. Compare this to what others



keep calling 'art' or at best the 'bed-time' stories that some publish 
on their web sites as 'gurus'. I think they are, but their approach (if 
you we can call as such) is nothing more that a collection of 
experiences they have collected over the years. IMHO, any perf turning 
approach must yield accurate and reproachable results using a clearly 
defined tools and steps. And it should be something that can be taught 
and used by DBAs without necessarily having 20 years of experience.



Having said that, I have 4 reservations on HS M-R approach ...






to know why NOW. You will find out when such issue strikes, you won't 
have the time or initiative to ask people on the call to go back and a 
gather a list so you can have time to instrument your database to 
collect stats. Specially, if your application users MTS, connection 
pools, or in large RAC environment.






emphasis is put on Oracle internals which are mandatory to understand 
performance. Also, I did not think enough emphasis was put on the 
resolution part and how these measure will work to resolve the issue.



IMHO, the HS M-R class, is an advanced class that I will not recommend 
as an initial step. I think this method worked great for HS group due to



the nature and magnitude of problems they get consulted for. At that 
level of consulting and visibility, all the necessary pre-requisite work



is probably have been done for them. But for everyday DBA performance 
issues, it will not help as much.



I have been involved in so many performance issues since I attended this



class, all of them have been diagnosed and resolved. However, only in a 
few of them I had to get to the level where I really needed to use M-R.



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http://www.freelists.org/webpage/oracle-l


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Received on Fri Sep 28 2007 - 09:44:43 CDT












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