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Home -> Community -> Usenet -> c.d.o.server -> Re: Q: Redo Log Switching
On 28 Oct 1997 13:39:21 GMT, "Andreas Hess" <ahess_at_truworths.co.za> wrote:
>
>Hi All
>
>Just a little something I'm confused about...
>
>According to the Oracle Backup and Recovery Handbook,
>a log switch is triggered when "Foregrounds are no longer
>able to allocate space in the redo log buffer".
>
I don't have this particular handbook here but there is either a misunderstanding or a "bug" in a text. The fact is that log switch ocurs only after the *online redo log file* is completely filed or DBA manualy forces log switch.
>I have a small (8k) log buffer. My redo log files are 10 Mb each (3
>groups).
>
>Q1: Why does a log switch need to occur just because
> there is no available space in the buffer ? Why can't
> the buffer be flushed to an online redo log file without
> triggering a log switch ?
As stated above, this exactly is the case - no log switch is forced because of redo buffer being flushed.
>Q2: Would a large redo log buffer reduce the number of
> log switches ?
Acording to above, obviously NOT.
>Q3: Follow on to Q2 - would a log buffer which is > the
> online redo log file be the most efficient ?
>
No. And in most cases it would be unpractical if not impossible to have log buffer greater than log files.
>Q4: Am I missing the point here ?
>
>Thanks in advance for any enlightenment...
>
>Regards,
>
>Andreas
Regards,
Jurij Modic Republic of Slovenia jurij.modic_at_mf.sigov.mail.si Ministry of Finance ============================================================The above opinions are mine and do not represent any official standpoints of my employer Received on Tue Oct 28 1997 - 00:00:00 CST
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