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

From: Kerber, Andrew W. <>
Date: Fri, 28 Sep 2007 09:44:43 -0500
Message-ID: <>

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-----
[] On Behalf Of Ted Coyle Sent: Friday, September 28, 2007 8:36 AM To:; 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
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
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.


-----Original Message-----
On Behalf Of fmhabash
Sent: Wednesday, September 26, 2007 2:14 PM To:
Cc: oracle-l
Subject: Re: Training for Oracle Performance tuning

I read the OraPub class description here Spec
. 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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Received on Fri Sep 28 2007 - 09:44:43 CDT

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