Re: switch logfile, checkpoint, active and inactive logfile

I guess you already know that

CURRENT = redo log file currently in use ACTIVE = redo log file not in use but is required for instance recovery INACTIVE = redo log file not in use and not required for instance recovery

That being said, may I point out that

"alter system switch logfile;"

returns control to you after the logfile is switched, which does not necessarily mean that it will complete the checkpoint by then. It is quite possible that the checkpoint completes some time after the switch or perhaps does not complete at all. Your alert logs will give you a better picture. The fact that your redologs are 100M each (pretty big) completion of the checkpointing could be delayed. Thus you are seeing the second redolog file as active. It is important that you check your alert logs and see what exactly is going on.

On the other hand

"alter system checkpoint;"

returns the control to you only after explicitly completing checkpoint, hence the redolog is show as inactive.

Hope that makes sense

//tc

<niy38_at_hotmail.com> wrote in message
news:b86q54$h97$1_at_oasis.ccit.arizona.edu...
> Please, thanks!
>
> Niy wrote:
> > I can not understand following: why switch logfile doesn't trigger
> > a checkpoint? only until I issue "alter system checkpoint", then
> > the "active" logfile change to "inactive"? I don't enable archivelog.
> >
> >
> >
> >
> > SQL> select * from v$log;
> >
> > GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
>
> ---------- ---------- ---------- ---------- ---------- --- ---------------
 -
> > FIRST_CHANGE# FIRST_TIM
> > ------------- ---------
> > 2 1 84 104857600 1 NO CURRENT
> > 11891725 22-APR-03
> >
> > 3 1 83 10485760 2 NO ACTIVE
> > 11887925 22-APR-03
> >
> >
> > SQL> alter system switch logfile;
> >
> > System altered.
> >
> > SQL> select * from v$log;
> >
> > GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
>
> ---------- ---------- ---------- ---------- ---------- --- ---------------
 -
> > FIRST_CHANGE# FIRST_TIM
> > ------------- ---------
> > 2 1 84 104857600 1 NO ACTIVE
> > 11891725 22-APR-03
> >
> > 3 1 85 10485760 2 NO CURRENT
> > 11893588 22-APR-03
> >
> >
> > SQL> alter system checkpoint;
> >
> > System altered.
> > SQL> select * from v$log;
> >
> > GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
>
> ---------- ---------- ---------- ---------- ---------- --- ---------------
 -
> > FIRST_CHANGE# FIRST_TIM
> > ------------- ---------
> > 2 1 84 104857600 1 NO INACTIVE
> > 11891725 22-APR-03
> >
> > 3 1 85 10485760 2 NO CURRENT
> > 11893588 22-APR-03
>
Received on Thu Apr 24 2003 - 14:53:31 CEST