Re: Why sometime redo log switch very fast?

On Sun, 6 Feb 2005 16:25:24 +0800, "music4" <music4_at_163.net> wrote:

>Greetings,
>
>Recently, we found a strange on our system. Our system uses Oracle 8.1.7.
>Each day, we can find a period that lasts about 10 minutes, during that
>period, from alartSID.log file, we can see redo log switches very fast.
>Normally, redo log switch each minute, but during that period, redo log
>switches each 20 seconds.
>
>From our program's log file, we are sure our program doesn't perform special
>operations at time. So we guessed there might be somebody did manually
>operations, like update, detele, etc. at that time. But nobody admit they
>did manually operations.
>
>So I just want to know is it possible that Oracle itself do something that
>cause redo log switch very fast?
>
>Regards,
>Evan
>

A redolog switch every minute is really undesirable, let alone every 20 seconds.
If you have a redolog switch every 20 seconds it simply measn your application is generating three times as much redolog volume. You can easily find out what is going on using logminer.

Oracle doesn't have any mechanism to increase the number of redolog switches.

--
Sybrand Bakker, Senior Oracle DBA