Re: interpreting statspack reports ( PX Deq )

Do we have to rely on v$pq_tqstat to find whether the wait Send Blkd occurs in the parallel to serial or parallel to parallel stage? If so, is it true that we can't see anything in v$pq_tqstat from a session other than the one running the parallel query?

Thanks.

Yong Huang

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:<1024039764.16314.0.nnrp-10.9e984b29_at_news.demon.co.uk>...
> The "PX Deq Credit: send blkd" is not necessarily
> an idle event, and can be indicative of a sub-optimal
> parallel execution plan.
>
> The significance of "Send Blkd" is that the process
> has some information to forward and it is being
> blocked. If this occurs in the "parallel to serial"
> stage of a "QC (range)" transfer, then it is an
> idle event, and the processes that are waiting
> their turn will be ticking over on this event every
> 2 seconds. If it is in a "parallel to parallel" phase,
> then each block is a time-wasting block, will
> affect total throughput time, and probably incurs
> the overhead of an o/s task switch.
>
>
> --
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
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Received on Fri Jun 14 2002 - 14:55:48 CDT