Re: Skewed Wait Times

From: Mogens Nørgaard <mln_at_miracleas.dk>
Date: Thu, 14 Feb 2002 07:50:14 -0800
Message-ID: <F001.0040F9E7.20020214064326@fatcity.com>

Well, why not ask the man himself? Jonathan - are you there?

Mogens

Rajesh.Rao_at_jpmchase.com wrote:

Nope. That version of v$system_event would also show me the max wait that was done on an event, and not just the total time waited. Its there in his book, somewhere in a chapter that also talks of v$filestat and IO tuning, I think.
Raj

  Connor McDonald <hamcdc_at_yahoo.co.uk>
  Sent by: root_at_fatcity.com
  02/09/2002 10:28 AM PST
  Please respond to ORACLE-L

  To:Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
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  Subject:Re: Skewed Wait Times

You're thinking of v$mystat, but v$session_event is
available in 'vanilla' oracle.

hth
connor

Rajesh.Rao_at_jpmchase.com wrote: > Hello All,
>
> After setting timed_statistics to true, I am finding
> something strange with
> the wait times in v$system_event for the event 'db
> file sequential read'.
> The wait times far exceed the uptime of the
> database. What I can think of
> is, say there are 10 sessions waiting for a single
> hot block for say 1 ms.
> The wait is actually for 1ms, but for the 10
> sessions it add to 10ms.
>
> Or that the times are skewed. I remember reading
> about this in 'Practical
> Oracle 8i' where Jonathan Lewis had addressed these
> issues. There was also
> a script in there to create your own version of
> v$system_event, reading
> from two x$ tables. I dont have the book handy with
> me now. Would someone
> be kind enough to forward the same to me?
>
> Thanks
> Raj
>
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Received on Thu Feb 14 2002 - 09:50:14 CST