Re: Way to much log switching!!!

From: Daniel Fink <Daniel.Fink_at_Sun.COM>
Date: Wed, 30 Jun 2004 15:21:56 -0600
Message-id: <40E32EF4.5060809@sun.com>

The only times I have been concerned with log switches were when they dramatically increased (in one case from 1 per 30 minutes to 3 per minute). Backtracking through oracle, we found users that were performing excessive activity ("I have not loaded the daily data in over 4 weeks, so I decided to load ALL of it today. Is that a problem?")

Log switches are like some metrics. By themselves they are not necessarily an indicator of a problem, but when the metric changes dramatically in a short period of time, you need to investigate why.

Regards,
Daniel Fink

Jeremiah Wilton wrote:
> On Wed, 30 Jun 2004 Rajesh.Rao_at_jpmchase.com wrote:
>
>

>>I dont think recovery is the issue. The issue could be performance, caused,
>>if not by frequent checkpointing, then by log switches. Does redo logging
>>not freeze during a log switch, since log buffer space wont be allocated
>>until the log switch is complete. So, in an hour, is it not better to have
>>3 log switches than 30?

>
>
> Well this is not normally a significant factor in most environments.
>
> But if someone thinks that people are spending time waiting on log
> switches, they can always look at v$system_event and find out if 'log
> file switch' comprises any significant proportion of waits.
>
> Otherwise, it is just conjecture, right?

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Received on Wed Jun 30 2004 - 16:18:51 CDT