Re: Is this Needed?
- From: stephen booth <stephenbooth.uk@xxxxxxxxx>
- To: dofreeman@xxxxxxxxxxx
- Date: Wed, 26 Oct 2005 16:23:50 +0100
On 26/10/05, Freeman, Donald <dofreeman@xxxxxxxxxxx> wrote:
> I just received a notice from our technical team leader that we were going to
> schedule a 'refresh' on our transactional database in order to improve
> performance. They are going to truncate and reimport the production schema.
> Is this technique useful for a 9i database? I'm thinking that in earlier
> versions of Oracle it might have been helpful but on the other hand I don't
> see any discussion of this on any board that I am monitoring. Is this a
> waste of time?
The only thing I can think of that that could do that might help
performance (emphasis on might) is if you have a lot of migrated rows
(rows that started out in one block and latrer moved to another block
as a result of being updated) or a lot of deletions of indexed rows or
updates of indexed fields resulting in lots of dead keys. As I recall
from training, unless it's another myth taught as fact on courses,
either of these could cause unnecessary physical IOs.
If you are having problems with migrated rows and dead keys then your
time might be better spent on a a few 'alter table..move'/'alter
index...rebuild' and trying to minimise reoccurances.
Stephen
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