Oracle-L: RE: how to force a log switch

From: Andrey Bronfin <andreyb_at_elrontelesoft.com>
Date: Mon, 19 Aug 2002 05:18:26 -0800
Message-ID: <F001.004B8C56.20020819051826@fatcity.com>

Thanks a lot to all who replied !

DBAndrey

03-9254520
058-548133
mailto:andreyb_at_elrontelesoft.com

-----Original Message-----
Sent: Sunday, August 18, 2002 6:36 PM
To: LazyDBA.com Discussion; Andrey Bronfin

After researching lot of issues with having smaller size redo logs , we opted for solution of switching ther redo logs at will using ALTER SYSTEM SWITCH LOGFILE using a cronjob , which works fine and keeps
the Standby upto date with the primary as will

We switch it every hr as per the activity in our env where the log are sized at 20 M .

Making them small would have performance impact to log writer and the archiver , while there is nothing to worry about if the Logs remained unfilled at the switch

HTHU Ankur Shah
Oracle DBA
DHR-GA
----- Original Message -----
To: "LazyDBA.com Discussion" <oracledba_at_lazydba.com> Sent: Sunday, August 18, 2002 10:47 AM

Ron , thanks a lot !
I know this solution , but:
there are certain pick-times when there are many activities going on against the DB. Therefore making the redo logs smaller will cause performance problems. So , i'd have this solution as a last resort, in case i will not find an init.ora solution.
Thanks again !

DBAndrey

03-9254520
058-548133
mailto:andreyb_at_elrontelesoft.com

-----Original Message-----
Sent: Sunday, August 18, 2002 3:14 PM
To: 'Andrey Bronfin'; 'LazyDBA.com Discussion'

The answer pretty simple - change the size of your logs. Log switching is a function of transaction volume. The fewer the transactions, the fewer the log switches. Consider that logs only switch when they are filled (or manually). So ,if there are insufficient transactions to fill your logs in 3 minutes, make your logs smaller. If your logs are switching every 10 minutes now, then create new logs that are 1/3 the size.

Having said all that, the other thing you could do is create a dbms_job that runs every three minutes and forces a log switch. It's not as pretty as right-sizing your logs, but it works.

R/
Ron Gawer

-----Original Message-----
Sent: Sunday, August 18, 2002 10:03 AM
To: LazyDBA.com Discussion

Dear gurus !
It's either a Sunday's dead brain or ...... Is there an init.ora parameter to force redo logs switch every 3 minutes or so ? ( the reason is that I need frequent log switches in order for the standby database to pickup changes frequently , i.e. to be "almost" in sync with the primary DB. And, off course, issuing "alter system switch logfile" in the application is not feasible ) Now, i only found parameters related to the frequency of the CHECKPOINTs and not log switches. Any help , please ...

DBAndrey

03-9254520
058-548133
mailto:andreyb_at_elrontelesoft.com

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Author: Andrey Bronfin
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Received on Mon Aug 19 2002 - 08:18:26 CDT

RE: how to force a log switch - SOLVED !