Re: log_checkpoint_timeout : what is exactly the meaning ?

"Richard Foote" <richard.foote_at_bigpond.com> wrote in message news:%6EJ8.1685$Hj3.5395_at_newsfeeds.bigpond.com...
> Just a slight clarification to Jonathan's post.
>
> "... you are telling Oracle (not) to ensure that no block may remain
> unwritten if its first change occurred more than 900 seconds ago" (Note
the
> elimination of the "(not)" after Oracle correctly changes the meaning of
the
> sentence)
>
> Cheers
>
> Richard

Thanks for that precision, but the sentence remains unclear for me. Isn't it "you are telling Oracle to ensure that no block may remain unwritten if its LAST change occurred more than 900 seconds ago" ?

>
> "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message
> news:1022789937.15172.0.nnrp-12.9e984b29_at_news.demon.co.uk...
> >
> > The answer depends on your version of Oracle.
> > Recently the meaning has changed - Oracle uses
> > an incremental checkpoint strategy to ensure that
> > the I/O subsystem is not flooded so ferociously at
> > end of log file. The log_checkpoint_interval and
> > log_checkpoint_timeout had their implementation
> > changed so that they act as lag events, rather
> > than triggering a checkpoint.
> >
> > For log_checkpoint_timeout=900, you are telling
> > Oracle not to ensure that no block may remain
> > unwritten if its first change occurred more than
> > 900 seconds ago.
> >
> >
> > --
> > Jonathan Lewis
> > http://www.jlcomp.demon.co.uk
> >
> > Author of:
> > Practical Oracle 8i: Building Efficient Databases
> >
> > Next Seminar - Australia - July/August
> > http://www.jlcomp.demon.co.uk/seminar.html
> >
> > Host to The Co-Operative Oracle Users' FAQ
> > http://www.jlcomp.demon.co.uk/faq/ind_faq.html
> >
> >
> >
> > vigi98 wrote in message ...
> > >Hi all,
> > >
> > >In my init.ora, the only two parameters about checkpoints are the
> > >following :
> > >
> > >log_checkpoint_timeout = 900
> > >log_checkpoints_to_alert=true
> > >
> > >Shouldn't I observe in the alert file the beginning of a new
> > >checkpoint every 15 minutes ? Apparently checkpoints behave as if I
> > >had not set the log_checkpoint_timeout, i.e. checkpoints are launched
> > >only when a redo log switch occurs. As my redo logs are 200Mb wide,
> > >there can be a very long time before a redo log switch occurs, in case
> > >of low traffic on the database.
> > >
> > >Have I misunderstood the signification of this parameter (I mean
> > >log_checkpoint_timeout ) ?
> > >
> > >Thanks in advance.
> >
> >
>
>
Received on Fri May 31 2002 - 03:34:05 CDT