Re: ORCLALRT.LOG doesn't contain timestamps!

I would seriously advise getting a hold of the 'Generic Oracle Documentation CD-Rom.

The issues here are more complicated than the book you're quoting implies. Even although it comes from Oracle Press, it is not a proper manual (unlike the contents of the Cd-Rom above).

If you were to see the paper copies of the Oracle Manuals from the Cd-Rom they would propably fill a small shelf at your bookshop!

Perhaps Oracle Press feel its better to give people some advice, albeit while simplifying other things. I can understand this up to a point, but I don't think you can rely on their books for real technical detail.

David P.

Oracle Certified DBA.

trea wrote:
>
> DNP <High.Flight_at_btinternet.com> wrote in message
> news:38EFF150.5B1B_at_btinternet.com...
> > trea wrote:
> > >
> > >
> > > everytime your redo logs switch your SGA is flushed. this clears out
 your
> > > db block buffers, shared pool, etc.
> >
> >
> > What a load of rubbish - modified buffers from the buffer cache are
> > written (copied, really) to the datafiles on disk as part of a
> > checkpoint which occurs at an impending log switch.
> >
> > One the checkpoint is complete, the contents of the red log buffer are
> > then written out to the redo log files.
> >
> > The shared pool is not touched! No buffers are removed from the buffer
> > cache. No data dictionary information in lost.
> >
> > Why can't some people read the manuals before the give advice???
> >
> >
> > David P.
> >
> > Oracle Certified DBA.
> >
>
> David;
>
> Begging your pardon but here is the quote from the manual where that
> statement came from:
>
> Book: Tuning Oracle
> Publisher: Oracle Press
> Page: 134
>
> "The problem with redo logs is that when a log switch occurs, the SGA is
> flushed...by flushing the SGA, you loose the benifits of keeping hot spots
> in memory. It is a very expensive process to retrieve information off of
> disk, compared to fetching information out of memory."
>
> That is just a portion of the topic in the manual. It goes on to say that
> you should make your redo logs a lot bigger and size them so they switch
> only durring lunch and off-hours etc. Also to set the
> LOG_CHECKPOINT_INTERVAL to a size greater than the redo logs file size and
> the set the LOG_CHECKPOINT_TIMEOUT parameter to 0 so that only when the redo
> log files fill up and cause log switch will you have a checkpoint.
>
> If I am missing something here or this information is incorrect please let
> me know. I would greatly appreciate it.
>
> Thanks;
>
> Trea
Received on Sun Apr 09 2000 - 00:00:00 CDT