Re: null event causing concern

Your status is 'waited short time' so in theory the wait reported is the last thing you waited for, and you are now using CPU.

The "null event" is a bug, and there are various patches through 9.2.0.3 and 9.2.0.4 to get rid of all occurrences of null event - but there are many cases in early 9's and some 8's where the event is set to the 'null event' as the real event ends.

You example looks like you did a single block read about 26 seconds ago, and have been burning CPU ever since.

The value 301 (given your comments) is
likely to indicate a temporary file. The P1 for the "db file single blocks read" events is file number + value of db_files parameter when the file is a tempfile.

I would guess that your db_files parameter is therefore 300.

Of course, I could be wrong - after all, the last actual wait might not have been a file read at all - but I can't think of any other event at the moment which would leave
your p1,p2,p3 looking the way they do.

--
Regards

Jonathan Lewis
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"John Ashton" <info_at_thunkbox.com> wrote in message
news:236d8572.0309190356.3fd0dbce_at_posting.google.com...


> We seem to have a pl/sql procedure that can occionally take a very

> long time to complete (> 13 hours). It is a big task but it would

> normally complete within 2 hours.

>

> As I'm not a DBA and I have limited rights so I have only been able

> get a partial view into what is happening (yes I have asked the

> support company X's DBA to investigate but there are political

reasons


> why I feel I need to look at this too).

>

> The only thing I can see that bothers me is the following from

> v$session_wait for the PL/SQL procedure session:

>

> EVENT         P1 P2 P3 TIME SECONDS_IN_WAIT STATE

> null event 301 87541 1 -1 26         WAITED KNOWN TIME

>

> Every time I see this null event, P1 is either 301 or 150 but I

don't


> know what this parameter refers to. I thought maybe it was file# but

> there are no files above 160.

>

> Can anyone tell me what this event might be?

>

> Thanks