Re: PARALLEL_EXECUTION_MESSAGE_SIZE

Hi, Mladen,
 parallel_execution_message_size is not a parameter "do not touch unless directed otherwise by Oracle technical support personnel".  I do not see such info in metalink/document.   Actually this parameter is very useful for parallel execution tuning. You maybe never tried it:). Doing standby database recovery tuning , tune this parameter with default value, can result in 4X recovery speed. This is very useful in deed, right?

 On 10/5/05, Gogala, Mladen <MGogala_at_allegientsystems.com> wrote:
>
> Yup. It's called "do not touch unless directed otherwise by Oracle
> technical support personnel". It determines the
>
> size of message interchanged by the query coordinator and slave processes.
> Oracle did not publish the message allocation
>
> methods, so by increasing the message size, you can drain your processes
> out of message structures and cause virtual
>
> deadlocks. I have few weeks of experience with Oracle and I've never seen
> parallel messages cause any problems.
>
> Remember, you should be tuning application, not an Oracle instance.
>
> The instance tuning approach was originated by Bruce Ellis and Clay
> Prestia, gurus of now dead but never quite forgotten
>
> OS, which was in my opinion far superior to any present OS, with the
> possible exception of zOS. The secret of performance,
>
> according to Clay Prestia, was to do things from memory and not from disk.
> I attended one of his classes in Bruxelles, Belgium,
>
> in which he was teaching us to look at paging and working sets, I/O,
> modified page writer (MPW sysgen parameters) and anything
>
> but using a profiler. He was advocating "tuning system" approach, instead
> of tuning program and even looking into the system
>
> if and only if the problem application is waiting on the system service.
> Bruce Ellis and Clay Prestia are spiritual fathers of
>
> the venerable "method C" described in the "Optimizing Oracle Performance"
> book by Cary Millsap & Jeff Holt.
>
> --
>
> Mladen Gogala
>
> Ext. 121
> ------------------------------
>
> *From:* zhu chao [mailto:zhuchao_at_gmail.com]
> *Sent:* Wednesday, October 05, 2005 7:43 AM
> *To:* Oracle-L
> *Subject:* PARALLEL_EXECUTION_MESSAGE_SIZE
>
> hi, all
>
> Have anyone noticed this parameter for oracle 9i? Document says max size
> is 64KB-1, and actually oracle round it to 64K. But if I try another size
> like 30k/60k, oracle does not change it. Anyone know the magic behind?
>
>

--
Regards
Zhu Chao
www.cnoug.org <http://www.cnoug.org>

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