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Re: Frequent log switches during sqlldr batch jobs

From: Frank van Bortel <fvanbortel_at_netscape.net>
Date: Wed, 02 Feb 2005 13:52:39 +0100
Message-ID: <ctqibn$lrv$1@news4.zwoll1.ov.home.nl>


thojens_at_gmx.de wrote:
> Hi,
>
> we are running 9.2.0.6 on Solaris. Each night, a bunch of sqlldr batch
> jobs are run and the redo log switches per hour increase dramatically:
> 100 and more per hour, while during normal production hours we're at a
> maximum of about 25 (usually much lower).
>
> However, I don't see any "Checkpoint not complete" messages in our
> alert file. Does it make sense to increase the redo log file size (The
> amount of data to be written would be same, wouldn't it)? What other
> possibilities do I have to check if there are performance problems when
> switching log files so often?
>
> Thorsten
>

The amount of data written would indeed be the same; there is some O/S overhead in closing a file, and opening a new one (new inode entry), but I wouldn't worry about it, unless you see switches within a second.

Query optimal_logfile_size in V$instance_recovery.

Ref: Performance Tuning Guide, Ch 4 "Sizing Redo Log files"

-- 
Regards,
Frank van Bortel
Received on Wed Feb 02 2005 - 06:52:39 CST

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