Re: Parallel Query: lots of wait time in event "PX qref latch"

From: Ivan Bajon <bajon_at_nospam@worldonline.dk>
Date: Fri, 2 Nov 2001 15:44:43 +0100
Message-ID: <3be2b14e$0$25390$edfadb0f@dspool01.news.tele.dk>

Hi Herman

Have you verified that 16 slaves are running? Check your parallel_max_servers and parallel_automatic_tuning parameters. Make sure the former is sufficiently high.

Hth,
Ivan Bajon

"Herman de Boer" <h.de.boer_at_itcg.nl> wrote in message news:bde5777e.0111010713.10d774b8_at_posting.google.com...
> Dear *,
>
> I am investigating a site running RDBMS 8.1.6.2.0, on HP V2500, UX11,
> 2Gb memory, a 4-cpu box hosting a ~400 Gb database with Parallel
> Query.
>
> Most time is spent in event PX qref latch, with parallel degree 8 (so
> 16 slaves are running), with about 50% idle time (as given by top).
> There is a certain amount of disk I/O, but far below the bandwidth.
> Complex sql-statements, mostly pctas.
>
> Anyone useful hints or advice or information what this event is about,
> and why so much time is spent in this one?
>
> Kind Regards,
>
> Herman de Boer
> IT Consultancy Group bv
Received on Fri Nov 02 2001 - 08:44:43 CST