Re: Re: max parallel query

i know there are no magic formulas, but im hoping for something better than trial and error. i would assume that parallel query helps most when:

1. are doing work off of multiple mount points.
2. Have alot more LIOs to perform than PIOs(such as sorts).

am i close on this?
>
> From: "M Rafiq" <rafiq9857_at_hotmail.com>
> Date: 2003/09/18 Thu PM 01:34:44 EDT
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Subject: Re: max parallel query
>
> Tanel,
> You are right. There is a param parallel_automatic(I don't remember exact
> name as I don't have access to database) which should be set to true and let
> system decide how many pq slave to be used. For max_parallel_server default
> is 5 and can be set to higher number which memory and cpu can handle. It
> is faster because it uses all system resources at a given time.
>
> Rarallel process can be used for large batch jobs during off-peak time.
>
> Regards
> Rafiq
>
>
> Reply-To: ORACLE-L_at_fatcity.com
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Date: Thu, 18 Sep 2003 08:39:44 -0800
>
> There is no simple magic formula how many parallel slaves you should have.
> It all depends on your CPU and IO utilization. Yes, utilization, because if
> your CPUs or IO are running at their limits already, you won't benefit from
> parallel execution at all. In fact PX may make the situation even worse,
> because it's designed to give you the results the fastest way, not the most
> efficient way.
>
> Tanel.
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Thursday, September 18, 2003 6:15 PM
>
>
> > We run multiple instances on the same server. My understanding is
> max_parallel_servers should be set to 4 x CPU. We have 4 CPUs which means
> 16.
> >
> > however, does this take into account multiple instances on the same
> server?
> >
> >
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> Author: Tanel Poder
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> Author: M Rafiq
> INET: rafiq9857_at_hotmail.com
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