Re: Memory utilization (was SGA/PGA and virtual memory)

s.griffiths_at_virgin.net wrote:
>
> On Fri, 14 Mar 1997 22:46:44 -0800, Gus Spier <gus_at_shirenet.com>
> wrote:
>
> >> > >
> >> > > Give a small SGA a try!
> >> > >
>
> If an oracle table is smaller than the initialisation parameter
> small_table_threshold then oracle will, by default, not cache the
> table. However, the OS will. If your application is dependant on a
> large number of table scans on tables which are larger than this
> parameter then the size of the oracle data cache will not greatly
> affect performance.
>
> However, the more memory you leave to the OS data cache then the
> faster your application will run!
>
> Alternatives you may like to consider are
> create more indexes
> increasing small_table_threshhold
> setting the CACHE parameter on CREATE TABLE
>

Most operating systems, AIX included I think, do not cache raw volumes. This leaves Oracle on its own for caching, and you have to give it more SGA to compensate for the lack of OS caching.

Of course, if you have a disk controller with a whopping big cache (e.g. the 2GB cache in our EMC box), it can improve even raw volume performance.

Bill Mansfield Received on Thu Mar 27 1997 - 00:00:00 CST