Re: Null Event in v$session_wait

db file scattered read and db file sequential read also end up as null event in v$session_wait. But the funny thing is that it is correct in v$session_event.

Anjo.

Jeremiah Wilton wrote:
>
> Null event is the bane of ORACLE 9.X. It pops up uner any
> circumstance that you really really need to know what a session is
> waiting on. Also, if you select your own wait event, it is always
> Null event. Result is about 15 bugs filed with Oracle by us alone.
> They promise it will get better in 10i, with some backports and patch
> releases for 9.2.
>
> --
> Jeremiah Wilton
> http://www.speakeasy.net/~jwilton
>
> On Tue, 18 Feb 2003, Jacques Kilchoer wrote:
>
> > I was looking this up on Metalink just the other day, and here is one of the
> > items of interest I found:
> > Doc ID: 408286.999
> > In my case I was trying to do a online index rebuild in 8.1.7 so I went with
> > support's explanation.
> >
> > <<NULL event shows up in v$session_wait for a session that does a short
> > timeout, without waiting for a particular resource. One place in the code
> > that this is done is during online index rebuild/creation. The session doing
> > the rebuild/create will try to get a DML lock no-wait, and if it fails to
> > get the lock, it sleeps on the "NULL event", and tries again. There are
> > probably other places where this occurs as well, however, this was one issue
> > discovered and documented in bug 1703940 (fixed in 9.2).
> > Gina Oracle Support Services>>
> >
> > -----Original Message-----
> >
> > I'm researching an performance issue with a Java program that appears to be
> > hung in the database. I query v$session wait and it's waiting on a "null
> > event". What exactly does this mean ? I've searched several books and
> > cannot find anything specifically on a null event wait event.
> > Any help would be appreciated.
> >
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Jeremiah Wilton
> INET: jwilton_at_speakeasy.net
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Anjo Kolk
  INET: anjo_at_oraperf.com

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