Re: What use is OCP ?

Yes!! Please! This is much worse than cross-posting!

Mike Ault wrote:

> Fellow Posters,
>
> Perhaps it is just me, but I find it really a pain to have to scroll
> to the very bottom of a tome to see your response. If I want to
> re-read the whole damn thing, I can go back to it. Place your
> responses at the top, then we can read them quickly and easily. Just
> my pet peave, and I treat it well...
>
> Mike
> "Richard Foote" <richard.foote_at_bigpond.com> wrote in message news:<oIDl9.42496$g9.121640_at_newsfeeds.bigpond.com>...
> > Comments are all in there somewhere ...
> >
> > "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message
> > news:an1pc3$rpq$1$8300dec7_at_news.demon.co.uk...
> > >
> > > Have any of you received the Sept/Oct issue of Oracle Magazine ?
> >
> > No I haven't. I'm still however recovering from the July/August edition. The
> > article on List Partitioning was hilarious (little self test: spot how much
> > List Partitioning was actually discussed). The first inside OCP article was,
> > how can I put it, somewhat simplistic (what's wrong with DELETE FROM
> > employee, ahhh right, no WHERE clause). Hmmm, not exactly mind stretching
> > material and not exactly setting much of a bar for these OCPs.
> >
> > Having said that though, there was still some good stuff in the mag.
> >
> > > Have you read the article by the Certification Director for OCP ?
> > > Would you like to see a few questions, answers, and comments
> > > about DBA fundamentals.
> > >
> > > Question 1:
> > > ----------------
> > > What is the minimum number of granules allocated at SGA start-up ?
> >
> > Correct answer - who cares ? Really, from an OCP point of this is a purely
> > theory, no practical benefit question.
> >
> > >
> > > Answer 1:
> > > ---------------
> > > The claim is three. The fact that my system
> > > always allocates at least 16MB to the shared
> > > pool alone, let alone the granules needed for the
> > > buffer and redo log when I start-up is a pity, but
> > > the answer might be right. However we then read:
> > >
> > > "On my database, I can check this by querying
> > > v$buffer_pool for LO_SETID which is 3"
> > > Why does the working data set of the default
> > > buffer pool prove anything about the number of
> > > granules ? If I have a KEEP and RECYCLE pool,
> > > the LO_SETID of the db_keep_cache_size is 1,
> > > the LO_SETID of the db_recycle_cache_size is 2.
> > >
> > > We also hear: "if the SGA_MAX_SIZE is less
> > > than 128M then the granule size is 4M, otherwise
> > > it is 16M" - perhaps he hasn't found that note on
> > > Metalink about granules of 8M on Windows 2K.
> > >
> > > Anyway - what's the point of asking someone about
> > > the notional minimum SGA of 3 granules (12MB) ?
> > > The executable is about 60M, and I'm not trying to
> > > run the thing on my cell-phone !
> > >
> > >
> > > Question 2:
> > > -----------------
> > > What four parameters most affect the SGA size ?
> > > a) sga_max_size
> > > b) shared_pool_size
> > > c) db_cache_size
> > > d) large_pool_size
> > > e) log_buffer
> >
> > Actually this question is really confusing. From one point of view, the
> > sga_max_size parameter is the one that *most* affects the SGA size. Trying
> > to set shared_pool_size to 100M, db_cache_size to 100M, large_pool_size to
> > 100M and log_buffer to 1 M. For some reason Oracle is not letting me. I
> > wonder if the sga_max_size being set to 64M has something to do with it ;)
> >
> > Also the non inclusion of the java_pool_size is interesting as it
> > potentially affects the SGA more so than the log_buffer.
> >
> > Again the question is somewhat academic. More beneficial questions would be
> > how do you size and tune these parameters appropriately.
> >
> > >
> > > Well, since the SGA_MAX_SIZE is the thing that
> > > is supposed to be the absolute limit on the number
> > > of granules you can allocate to the others it clearly
> > > has to be the other four. After all, you're not really
> > > 'affecting' the size of something if all you doing is
> > > stopping it from getting any bigger !
> > >
> > > Answer 2
> > > --------------
> > > Yup, sga_max_size is the one wrong answer.
> > >
> > > We also read "The sga_max_size is determined by
> > > the size of the other memory structures". Well,
> > > yes, if you let it default - but the sga_max_size is
> > > the thing you are supposed to set (if you are being
> > > a good DBA) so that you can vary the others at need.
> > >
> > >
> > > Question 3:
> > > -----------------
> > > Which command would you execute to decrease
> > > the size of the shared pool from 50MB to 20MB ?
> > > a)....
> > > b)...
> > > c) alter system set shared_pool_size 20m;
> > > d) alter system set shared_pool_size = 20m;
> > >
> > >
> > > Answer 3:
> > > --------------
> > > (d) - perfectly correct, perfectly pointless question.
> > >
> > > alter system set shared_pool_size 20m
> > > ORA-00927: missing equal sign *
> >
> >
> > I'm sorry Jonathon but this error message has me stumped. What can it
> > possibly mean ? I've tried alter system set shared_pool_size equal 20m and
> > the bugger still complains !! I'm beginning to think it has something to do
> > with competitive swimming. There, pool sizes must be 50M (as currently set)
> > or 25M for short courses. Perhaps the error message is suggesting I can only
> > reduce the pool size to 25M ...
> >
> > >
> > > I don't care if the DBA doesn't remember that there is
> > > supposed to be an equal sign - if he can't spot the problem
> > > when Oracle gives him the error message he probably never
> > > got past filling in the application form for the interview.
> > >
> > >
> > > Question 4:
> > > -----------------
> > > Oracle Managed Files are established by setting
> > > what two of the following parameters.
> > > a) db_file_create_dest
> > > b) db_file_name_convert
> > > c) db_files
> > > d) db_create_online_log_dest_n
> > >
> > > Answer 4:
> > > ----------------
> > > (a) and (d)
> > >
> > >
> > > wait a moment - there's no such parameter as
> > > db_create_online_log_dest_n. There is
> > > db_create_online_log_dest_1,
> > > db_create_online_log_dest_2,
> > > db_create_online_log_dest_3,
> > > db_create_online_log_dest_4,
> > > db_create_online_log_dest_5,
> > > and the manual suggests that you set at least
> > > two of them. And of course the manual also
> > > tells you that you don't need to set any of them,
> > > as db_file_create_dest will do on its own.
> > >
> > >
> > > Is this hair-splitting - well if 3C is definitely wrong
> > > because of an '=' is it safe to assume that 4D is right
> > > when it has a letter instead of a number ?
> >
> > Picky picky but point taken.
> >
> >
> > >
> > > Of course, the article does continue to point out
> > > that in fact "you can set either or both". Of course
> > > the Database reference manual happens to say that
> > > there is no default value for db_create_file_dest,
> > > so I thought I'd have a go creating a database with just
> > > db_create_online_log_dest_1 - did it work ? Yes -
> > > but it built the data files in $ORACLE_HOME/dbs,
> > > which isn't really the ideal place for them.
> > >
> > >
> > > So I have learnt something today.
> >
> > I think these articles are doing some good by highlighting to anyone who
> > doesn't already know how absolutely dreadful the current OCP program really
> > is. So Oracle deserves some credit for trying the discredit it's own OCP
> > program in it's own mag.
> >
> > The "practical" certification exam is definitely a step in the right
> > direction but as I've stated before, some significant issues still need to
> > be addressed before anyone even pretends to take OCP seriously.
> >
> > Cheers
> >
> > Richard
> > >
> > >
> > > --
> > > Regards
> > >
> > > Jonathan Lewis
> > > http://www.jlcomp.demon.co.uk
> > >
> > > Next Seminar dates:
> > > (see http://www.jlcomp.demon.co.uk/seminar.html )
> > >
> > > ____England______September 24/26, November 12/14
> > >
> > > ____USA__________November 7/9 (MI), 19/21 (TX)
> > >
> > > The Co-operative Oracle Users' FAQ
> > > http://www.jlcomp.demon.co.uk/faq/ind_faq.html
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
Received on Sun Sep 29 2002 - 15:18:21 CDT