Expected Impact of Changing Logging Type

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Matt - 16 Mar 2006 15:51 GMT

I have a production database that I need to change the logging type
from circular to archived so that I can do online backups. The
database is not particularly large, but is used by many people. What
impact from the users perspective can I expect? Is the only impact
behind the scenes in the db manager? Thanks in advance for any help.
Matt

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Knut Stolze - 16 Mar 2006 15:53 GMT

> I have a production database that I need to change the logging type
> from circular to archived so that I can do online backups. The
> database is not particularly large, but is used by many people. What
> impact from the users perspective can I expect? Is the only impact
> behind the scenes in the db manager? Thanks in advance for any help.

There will be no impact no the user. DB2 has to manage the log files now
and as long as there is enough disk space (or a proper user exit archiving
the completed log files away), you don't have to worry.

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Knut Stolze
DB2 Information Integration Development
IBM Germany

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Matt - 16 Mar 2006 15:56 GMT

Thanks for the quick response. I appreciate it very much. Matt

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Gert van der Kooij - 16 Mar 2006 16:45 GMT

> > I have a production database that I need to change the logging type
> > from circular to archived so that I can do online backups. The
[quoted text clipped - 5 lines]
> and as long as there is enough disk space (or a proper user exit archiving
> the completed log files away), you don't have to worry.

But after changing the logging type a full offline backup is needed,
which means no users are allowed to connect. So the right time for
changing the logging type is just before creating a full backup.

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Eugene F - 16 Mar 2006 20:07 GMT

In general database logging affects performance of bulk data
modifications from SQL (INSERT, UPDATE, DELETE) because the default
behaviour is to log table data updates. However, if your database is
fairly small it may not be an issue. After you turned on the logging
you would need to monitor performance anyways to see whether
performance degrades.

-Eugene

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Ian - 16 Mar 2006 20:38 GMT

> In general database logging affects performance of bulk data
> modifications from SQL (INSERT, UPDATE, DELETE) because the default
> behaviour is to log table data updates. However, if your database is
> fairly small it may not be an issue. After you turned on the logging
> you would need to monitor performance anyways to see whether
> performance degrades.

Yes, but this is irrelevant when comparing circular to archive logging.
DB2 always uses the transaction log for recovery. It's just a matter of
whether we want to keep the old log files or not.

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Eugene F - 16 Mar 2006 20:46 GMT

Agreed... sorry for the confusion... :-(
-Eugene

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