Re: ORCLALRT.LOG doesn't contain timestamps!

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