Morten, would you care to comment (in your usually nice and easy manner?) If was, after all, you who came with the "unlearn" quote below.
Best regards,
Mogens
DENNIS WILLIAMS wrote:
Mogens - I posted this note back in October.
-----Original Message-----
From: DENNIS WILLIAMS
Sent: Saturday, October 05, 2002 4:08 PM
To: '[EMAIL PROTECTED]'
Subject: Oracle Performance Tuning Class - update
List
I spent last week at an official Oracle Education Oracle9i Performance Tuning Class, and here is some of the non-technical stuff I learned.
- Oracle is teaching the wait interface more and more. In fact, they are updating the curriculum next month to emphasize the wait interface even more (lucky me).
- Just how the wait interface is emphasized may depend quite a bit on the instructor, despite what the materials say. My observation is that our opinions are based on what we have experienced and our interpretations of those experiences. So we will probably still have some instructors that will still feel that the wait interface is a passing fad and if you really want to straighten out a database, you need to get in there and improve the BHR (Buffer Hit Ratio).
- My instructor was John Hibbard. He is excellent, and I would highly recommend him. He went well beyond the class materials to providing papers he has researched and presented himself, as well as other sources, including papers from Cary Milsap and Jonathan Gennick who participate on this list. When you get through his class, you really feel you have been taken to a whole new level of Oracle knowledge. He is also heavily involved in selecting and preparing the official Oracle training materials for the courses he teaches. Besides Performance Tuning, he teaches several other Oracle classes. Most of the people in my class happened to be more experienced with Oracle, and John did a good job of answering advanced questions with some depth, but not leaving the newbies in the dust.
- A funny observation on buffer hit ratio vs. wait interface. The last day of class is an opportunity to take a really screwed-up database and apply a little of what you have learned. The first scenario is titled "Buffer Cache". So you run the workload assignment and STATSPACK and look at the BHR and say "wow, that is bad", increase the buffer pool, and rerun the workload and STATSPACK. The BHR hasn't changed much, so the tendency is to dumbly bump the buffer pool even more and go again. Then you look down at the top 5 waits section just below on the first page of the STATSPACK report and see that the big wait item is "Scattered Read". Then you go "dope slap" and realize this schema is missing some critical indexes and table scanning it's little heart out. I just found it ironic that some people have reported that some of the Oracle instructors emphasize the BHR too much when the first Workshop Scenario has a great example of why focusing on BHR can't solve many problems. But again, we have experience vs. interpretation of experience. A real died-in-the wool BHR fanatic would probably claim that BHR had solved the problem because the first indication that something was wrong was spotting the bad BHR, which led to other investigations.
Dennis Williams
DBA
Lifetouch, Inc.
[EMAIL PROTECTED]
-----Original Message----- Sent: Tuesday, February 25, 2003 10:24 PM To: Multiple recipients of list ORACLE-L
Yeah, if you've taken the performance exam, you must now unlearn what you have learnt, to quote from Starwars. I've considered creating a one- or two-day class that would put people into the right track of thinking after having studied and passed that exam. The other exams are more or less fine. The tuning one really - ahm - could be improved...
Mogens
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> wrote:
Guys,
I took this exam after 12 hours studying and missed 4 questions. I studied using the self-test software (few practice exams) some memorization and the student guides from the oracle 8 tuning - read through once and not every item (not 8i class) - where the heck was statspack in the examm, btw? I took it in 20 minutes. Only the network one to go. Can't wait to get this done so can do the 9i upgrade exam - then wishing to concentrate on certification relating to 9ias - is there such a beast?
-----Original Message----- <mailto:[EMAIL PROTECTED]> ] Sent: Tuesday, June 11, 2002 11:14 AM To: Multiple recipients of list ORACLE-L
Arslan - I'm hoping you get some good replies since I plan to take this exam
next.
I just took the B&R last week. The resource that helped me the most is: Oracle8i Certified Professional DBA Practice Exams by Jason S. Couchman http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?userid=1G60ZMKA1
<http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?userid=1G60ZMKA
1> J&isbn=0072133414 (hopefully this link will work, it will be broken into two
lines which you must patch back together).
Dennis Williams DBA, 20% OCP Lifetouch, Inc. [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
-----Original Message----- Sent: Tuesday, June 11, 2002 7:38 AM To: Multiple recipients of list ORACLE-L
I will enter my last exam at next week. Could DBAs which have this exam give some advice.
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