Re: V$LOG_HISTORY on 7.3.4, Q on SQL&PL/SQL Annotated Archives book

Not to step on Loney's (Kevin Looney? sp?) toes, the 30 minute rule does not apply to everyone. In all actuallity, there is no rule on the frequency of log switches. It all depends on the business needs of the company. For example, I was in a situation in which the company did not want to spend money on a High availability solution, yet didn't want to lose more than 5 minutes of transactions.

As far as looking at the frequency of log switches, you can look at your alert<sid>.log file. You can use the "grep" command in UNIX to filter only the log switches.

Good Luck,
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In article <xu3yEDAQiep2Mwds_at_camk.demon.co.uk>,   Andy Hardy <Andy.Hardy_at_camk.demon.co.uk> wrote:
> Hello,
>
> I've just been browsing through Loney and Carmichaels book 'Oracle SQL &
> PLS/SQL Annotated Archives' from Osborne Press.
>
> The section that I'm looking at is about REDO logs and suggests that
> they should be switching no more frequently than every 20-30 minutes.
> The text and the piece of SQL to verify this state that the
> V$LOG_HISTORY view shows the last 100 log switches.
>
> This doesn't seem to match my db which has over 1600 switches in its
> v$log_history!
>
> So, what is the truth behind the view? And, is the 20-30 minute rule of
> thumb of practical use?
>
> Andy

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