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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Skewed Wait Times
And here's the answer from Jonathan:
The script was an extended version of the definition of gv$system_event from v$fixed_view_definition which included the MAX_WAIT value, which for some reason is usually missing from v$system_event even though it is present in v$session_event.
The text is as below - although it now needs some modification for getting maximum information for Oracle 9 which uses micro-second timing.
create or replace view v$max_system_event
as
select
d.kslednam event, s.ksleswts waits, s.kslestmo timeouts, s.kslestim tot_csecs, s.kslesmxt max_csecs
x$kslei s,
x$ksled d
where s.ksleswts != 0
and s.indx = d.indx
and d.inst_id = userenv('instance')
and s.inst_id = userenv('instance')
Jonathan Lewis
Mogens Nørgaard wrote:
> Well, why not ask the man himself? Jonathan - are you there?
>
> Mogens
>
> Rajesh.Rao_at_jpmchase.com <mailto:Rajesh.Rao_at_jpmchase.com> wrote:
>
>> Nope. That version of v$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$filestat and IO tuning, I think.
>>
>> Raj
>>
>>
>> Connor McDonald <hamcdc_at_yahoo.co.uk> <mailto:hamcdc_at_yahoo.co.uk>
>> Sent by: root_at_fatcity.com <mailto:root_at_fatcity.com>
>> 02/09/2002 10:28 AM PST
>> Please respond to ORACLE-L
>>
>> To:Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>> <mailto:ORACLE-L_at_fatcity.com>
>> cc:
>> bcc:
>> Subject:Re: Skewed Wait Times
>>
>>
>> You're thinking of v$mystat, but v$session_event is
>> available in 'vanilla' oracle.
>>
>> hth
>> connor
>>
>> --- Rajesh.Rao_at_jpmchase.com <mailto:Rajesh.Rao_at_jpmchase.com> wrote: >
>> Hello All,
>> >
>> > After setting timed_statistics to true, I am finding
>> > something strange with
>> > the wait times in v$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
>> >
>> > --
>> > Please see the official ORACLE-L FAQ:
>> > http://www.orafaq.com
>> > --
>> > Author:
>> > INET: Rajesh.Rao_at_jpmchase.com <mailto:Rajesh.Rao_at_jpmchase.com>
>> >
>> > Fat City Network Services -- (858) 538-5051 FAX:
>> > (858) 538-5051
>> > San Diego, California -- Public Internet
>> > access / Mailing Lists
>> >
>> --------------------------------------------------------------------
>> > To REMOVE yourself from this mailing list, send an
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>> =====
>> Connor McDonald
>> http://www.oracledba.co.uk (mirrored at
>> http://www.oradba.freeserve.co.uk )
>>
>> "Some days you're the pigeon, some days you're the statue"
>>
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>> --
>> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> --
>> Author: =?iso-8859-1?q?Connor=20McDonald?=
>> INET: hamcdc_at_yahoo.co.uk <mailto:hamcdc_at_yahoo.co.uk>
>>
>> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>> San Diego, California -- Public Internet access / Mailing Lists
>> --------------------------------------------------------------------
>> To REMOVE yourself from this mailing list, send an E-Mail message
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>> -- Please see the official ORACLE-L FAQ: http://www.orafaq.com --
>> Author: INET: Rajesh.Rao_at_jpmchase.com
>> <mailto:Rajesh.Rao_at_jpmchase.com> Fat City Network Services -- (858)
>> 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet
>> access / Mailing Lists
>> --------------------------------------------------------------------
>> To REMOVE yourself from this mailing list, send an E-Mail message to:
>> ListGuru_at_fatcity.com <mailto:ListGuru_at_fatcity.com> (note EXACT
>> spelling of 'ListGuru') and in the message BODY, include a line
>> containing: UNSUB ORACLE-L (or the name of mailing list you want to
>> be removed from). You may also send the HELP command for other
>> information (like subscribing).
>
>
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Mogens =?ISO-8859-1?Q?N=F8rgaard?= INET: mln_at_miracleas.dk Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Mon Feb 18 2002 - 17:23:36 CST
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