Re: Performance difference between 2 machines

"DA Morgan" <damorgan_at_psoug.org> wrote in message news:1119307340.321454_at_yasure...
> Matthias Hoys wrote:
>
>> But, if I use a (low) block size of 4k, won't I risk ending up with lots
>> of chained rows for "wide" tables (and thus double i/o to get those rows)
>> ?
>
> Possible. But we have no way of knowing what your average and maximum
> row lengths are from what you have posted. Or if your tables are
> properly normalized or have been flattened and thus have row sizes far
> larger than they should be.
>
> You need to work these things out for yourself based on analysis of your
> application.
> --
> Daniel A. Morgan
> http://www.psoug.org
> damorgan_at_x.washington.edu
> (replace x with u to respond)

Regarding the AIX filesystem block size : when I look at the properties of our enhanced journaled filesystems (JFS2), the unit size = 512 bytes and the filesystem block size = 4096 bytes. So what's the difference between unit size and block size ?
One of our 8.1.7 DWH databases (which needs to be migrated to Oracle 10g) has a block size of 16k, so what would be the reason for this ? (it was installed a long time ago by an external consultant). Is there any way to estimate the optimal block size for an existing database ?

Matthias Received on Tue Jun 21 2005 - 12:36:33 CDT