I concur with Dennis. I too came off a Oracle Ed Tuning class last week and
had a good instructor (who btw used John Hibbard's excellent presentation on
Redo/RBS _as_well_as Cary's 'Why a 99.9% BHR is not Ok'). Maybe, just maybe,
we will get there (i.e. a Non-BHR world!)
John Kanagaraj
Oracle Applications DBA
DBSoft Inc
(W): 408-970-7002
Disappointments are inevitable in Life, but discouragement is optional. You
decide!
** The opinions and statements above are entirely my own and not those of my
employer or clients **
> -Original Message-
> From: DENNIS WILLIAMS [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, October 05, 2002 3:13 PM
> To: Multiple recipients of list ORACLE-L
> 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]
>
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> Author: DENNIS WILLIAMS
> INET: [EMAIL PROTECTED]
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