Re: Data Buffer Cache

"Michael J. Moore" <hicamel_x_the_spam_at_attbi.com> wrote in message news:<P43h9.435668$me6.49737_at_sccrnsc01>...
> Howard,
> Since you teach this stuff, you might be interested in my students come to
> you with
> crazy ideas like mine. I know that you have flat out stated that this
> information
> is WRONG, but for the record, I'd like to give you the entire quote.
>
> On page 129 of OCP Oracle 9i Database: Fundimentals 1 Exam Guide it says:
>
> "The events that occur at log switch are as follows. First, LGWR stops
> writing
> the redo log it filled. Second CKPT signals the DBWn to fluch the dirty
> buffers into
> the data files and finally CKPT updates the control files and the data file
> headers
> with the checkpoint information. With the checkpointing tasks complete, the
> LGWR will be allowed to start writing into the next redo log group with a
> new
> sequence number."the checkpointing tasks complete
>
>
> It seems clear that the authors intend us to understand that
> 1) LGWR 'waits' until it is "allowed to start writing".
> 2) What does it wait for? It waits for "the checkpointing tasks complete".
>
> Granted there is nothing here that says anything waits for DBWn to finish,
> but it seems that the author at least intends us to believe that LGWR waits
> for CKPT!
>
> Since I don't have the source code in hand, I can only take the word of
> people like you.
> Perhaps if you have some pull with Oracle, you can get them to proof read
> their own
> damn documentation.
>
> <RANT> -- skip this if you are in a hurry.
>
> I have found more than 20 errors in the OCP Oracle 9i Database: Fundamentals
> 1 Exam Guide Authorized by Oracle Press! These are blatant errors that
> anybody can check for themselves such as 'you can determine the current
> sequence number from V$CONTROLFILE_RECORD_SECTION' or 'alter datafile
> resize' is a command that can be used to increase the size of a tablespace.
> It is clear that NOBODY proof read this book. Over the years I have
> witnessed an ever increasing decline in the quality of published materials
> especially in the technical field. I think we deserve better. I don't think
> that Osborne press and others should be allowed to toss together books of
> such poor quality and charge the public $50.00 for the privilege of proof
> reading them. For this, I give Osborne and Oracle Press the highest position
> in my personal Publisher's Hall of Shame.

I have found errors like this in every book. Some are so funny I consider
them fodder for .sig's. But I'm too lazy, and of course I don't think it
is really fair to hold a few typos or errors against someone who's taken
the time to write a whole book. On the other hand, anything published is,
and should be, fair game. I've had authors ask me to proof their books,
and turned them down because inevitably I'm too busy doing actual non-bleeding-edge work to give it a fair go (or else doing no work at all and not have access to resources to check things!). The last time anyone offered to _pay_ me todo such things was in college, and at the time it didn't seem as much fun
as being a scientist (man, I wish they had Dexter's Laboratory when I was
a kid!). With that as a preamble, I'd like to say I agree with the rant
insofar as there is an industry to crank crap out, but overall the quality
of information available about Oracle is as high as it's ever been, and I
don't mean that as a slam. Oracle docs in the "old days" (7 and before)
were notoriously bad at times, and the commercially available books were
often vague or useless before 7, with some notable exceptions. I still
haven't seen anything as bad as the Oracle on Solaris install guide with the
instructions for a different unix. Maybe the Velpuri backup scripts that were exactly the same for 7 and 8 (completely ignoring RMAN, which was perhaps a good thing contemporaneously).

I think as we learn more, it is easier to spot the little mistakes. And we
should all post them in this ng for all-time reference (ever try to download a corrections list from a site that no longer exists?). I'd like to see
a thread of "funniest typos," myself.

>
> </RANT>
>
>
>
> Sorry if this is becomming tedious for you.
>
> regards,
> Mike> >
> > Not true at all.
> >
> > Really, this is DBA-101. There is no mystery about it -or at least, there
> > shouldn't be. I teach this on Day 1 of the introductory DBA course. It's
> > basic stuff.
> >

On usenet, nobody knows it's your first day.

jg

--
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Performance Tuning and Network Administration Study Guide.