---- Message from Ronny Egner <Ronny.Egner@(protected) ------
>Hi list,
>
>i am struggling with i/o benchmarking and have a few questions:
>
>Our central NAS system has performance issues with
>nfs on solaris. When writing/reading over a gbit-link we see
>"only" 35 mb/s within a single thread. When adding a second
>thread (or process) the throughput increases - up to 80 mb/s with 4
>threads (or processes).
>
>However when writing data to disk with lets say 4 dbw processes
>we can max out the 80 mb/s. But how does reading from disk relates
>to that ? Lets say we do a full table scan in a single session and
>therefore have to read the whole table - does oracle use more than
>one process (or thread) to do that (remember my problem: one session
>or thread can only read 35 mb/s at maximum speed) ?
>
>--
>
>Mit freundlichen Grüßen
>
>Ronny Egner
>Diplom-Ingenieur (BA)
>

Parallel query (PQ) will do exactly that (split a full table scan in more parts
and then let multiple processes process the parts in parallel).

Caveat: By using PQ you will optimize a single session but with a higher total
resource consumption (caused by the need for coordination between the
parallel processes).

Martin Berg

Med venlig hilsen
Martin Berg

mobil: +45 30 35 58 68
email: martin@(protected)
web: www.berg-consult.com

--
To unsubscribe, email: suse-oracle-unsubscribe@(protected)
For additional commands, email: suse-oracle-help@(protected)
Please see http://www.suse.com/oracle/ before posting