RE: PARALLEL_EXECUTION_MESSAGE_SIZE

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.  

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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?    

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http://www.freelists.org/webpage/oracle-l Received on Wed Oct 05 2005 - 09:21:55 CDT