Re: any single serial session will never get more than 5% of pga

Notes in-line

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

  The educated person is not the person
  who can answer the questions, but the
  person who can question the answers -- T. Schick Jr

One-day tutorials:
http://www.jlcomp.demon.co.uk/tutorial.html

Three-day seminar:
see http://www.jlcomp.demon.co.uk/seminar.html ____UK___November

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Sunday, December 28, 2003 12:39 AM

> Hi Jonathan,
>
> I'm not sure what you really think about this new feature!

I view the feature as a positive step forward.

Instead of a DBA having to guess an artificially low limit on the sort_area_size because (say) 1200 users might be connected to a machine with 4GB of memory, you now give Oracle a directive like:

    I have 1.5GB available for sort operations;     please be as generous as you can when the     demand for memory is low, and ration it carefully     when the demand is high.

In theory, this ensures that more processes get in-memory sorting because there is a known spare capacity - in practice, the algorithms and options for over-ride will, no doubt, evolve over time.

> Are you saying that Oracle is capable now of releasing the extra memory
> something it was not capable of before?

Yes

> If yes, then what does it have to do with the work policy?
>

Nothing - but since the O/S used to take care of the problem by paging out unused memory there was little point in fixing something which wasn't totally broken.

On the other hand, if you are trying to operate a policy of maximising the amount of memory you give to a session, based on your estimates of expected data volume, it makes sense to use code that allows a session to de-allocate memory properly.

> I see this feature useful (not really) for a database application that
hosts
> N concurrent sessions
> while the amount of available resources is capable of running only N / m
> sessions.
> Where m is any integer.
>
> In different words, it's the choice when we don't have the required
> resources to run the app efficiently without restriction to the
performance
> and by using it, it will be able to torture any session that is asking for
> memory and give it enough guilt not to ask for it again and just try to
get
> the job done by any means :)

Now, if the techies on Redwood Shores could get the concepts of hungry and greedy into the code, perhaps we wouldn't have to do any more tuning ever again ;)

>
> Regards,
>
> Waleed
>
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).