RE: PARALLEL_EXECUTION_MESSAGE_SIZE

Years ago when I was helping a group move from an OPS database to a Sequent, we ran into issues with PQO. These are some of my notes I took when watching the system. Maybe they will help you. Take it with a grain of salt the db version was - 8.1.5.

Info on each PX message wait:

 Currently waiting on:PX Deq: Execution Msg - PQ slave is waiting to be told what to do.

                This is one of the main events used in a parallel query 
                dialogue as the slave is told to parse / execute / fetch etc.. 

 Currently waiting on:PX Deq: Join ACK - When setting up PQ groups of slaves we wait for them to

                join the group. 

Currently waiting on:PX Deq: Execute Reply - QC is waiting for a reply

 Currently waiting on:PX Deq: Signal ACK -

Dependency:     We are dependent on the producer. 
Advise:         If the process is often waiting for data then look at the 
                execution plan/s and degree of parallelism. 

Currently waiting on:PX qref latch -
Each process queue has an associated qref latch, which needs

                to be acquired before the queue buffers can be manipulated. 

Currently waiting on:PX Deq: Table Q Normal Currently waiting on:latch free   

It seems that we may be falling into this problem: PARALLEL QUERY DOES NOT SCALE IN 8.1 WHEN # OF DISKS IS SMALL RELATIVE TO DEGREE    -----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Steve Rospo Sent: Wednesday, October 05, 2005 2:51 PM To: Oracle-L
Subject: RE: PARALLEL_EXECUTION_MESSAGE_SIZE

I found this page which was very interesting: http://doug.burns.tripod.com/px8.html

"Partial Message Event

• PX Deq: Msg Fragment

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