Re: db file scattered reads
- From: David Roberts <big.dave.roberts@xxxxxxxxxxxxxx>
- To: tim@xxxxxxxxx
- Date: Sun, 5 Dec 2010 15:14:00 +0000
You have correctly identified profiles as a potential solution. Another
poster has also suggested, buffering strategies, using the keep pool
to achieve that goal.
Another responder as suggested manipulating the indexes, which, with
negotiation with your supplier you should consider.
Between these suggestions are either real or artificial manipulation of the
index statistics.
At the positive end, this could be a re-organisation of the index (through
an ordered reorganisation of the table (by CTAS) to make the use of a good
index cheaper.) or by the manipulation of oracle statistics
as recommended by Wolfgang.
OTOH, if the dataset is large, you may need to confider partitioning.
Dave
PS, you may find only a minority of participants on this
list recommend publications by Rampant press.
My personal preference is:
Troubleshooting Oracle Performance
by
Christian Antognini
On Wed, Dec 1, 2010 at 9:00 PM, Tim Gorman <tim@xxxxxxxxx> wrote:
> Lyall,
>
> Regarding your comment that this is a "off-the-shelf application that you
> can't touch": adding custom-built indexes generally does not violate
> support for 3rd-party off-the-shelf applications. The main requirement is
> usually that you build them in such a way that they are easily identifiable,
> easily dropped and re-created, and not created so as to disrupt product
> patching, etc. I'm sure lots of folks on this list have lots of advice on
> this, covering a wide variety of COTS apps. Perhaps someone on this list is
> managing the same application as well?
>
> Please verify with your application vendor on their policies for support
> for custom-built indexes?
>
> Hope this helps...
>
> Tim Gorman
> consultant -> Evergreen Database Technologies, Inc.
> postal => 13087 West Cedar Drive #225, Lakewood CO 80228
> website => http://www.EvDBT.com/
> email => Tim@xxxxxxxxx
> mobile => +1-303-885-4526
> fax => +1-303-484-3608
> Lost Data? => http://www.ora600.be/ for info about DUDE...
>
>
> On 12/1/2010 1:04 PM, lyallbarbour@xxxxxxxxxxxxxxx wrote:
>
> Hello everyone,
> From what i understand in my reading of this wait event, it happens the
> most with Fast Full Table Scans. As we all know, FFTS's aren't necessarily
> a bad thing. Looking through ADDM's and ASH reports from one of our
> databases, db file scattered reads on one table is the main culprit for the
> bottlenecks on this system. This is an off the self application that i
> can't touch, so the only SQL tuning i can do is with SQL Profiles. Is there
> anything i can do under the scenes to release some of this bottleneck? Move
> the table into it's own tablespace? Change the storage settings? That's
> one thing i can't find through google, is what to do if you get db file
> scattered reads. I'm still waiting for my tuning guide from Rampant, it's
> on backorder...
>
> Thanks,
> Lyall
>
>
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