Re: many seconds waiting for I/O?

Hi Norman

If it was sql*net messages why the event shows db file sequential read?

Alex


On 7/27/07, Dunbar, Norman <norman.dunbar@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
>
> Morning Alex,
>
> >> I have a batch process running and it seems that it's
> >> waiting for I/O all the time, the strange thing is it shows
> >> 400 seconds waits!
> >>
> >> EVENT                      CONSISTENT_GETS SPID
> >> WAIT_TIME SECONDS_IN_WAIT STATE                     SEQ#
> >> -------------------------- --------------- ------------
> >> ---------- --------------- ------------------- ----------
> >> db file sequential read             212532 25879
> >>    -1             374 WAITED SHORT TIME          892
>
> The STATE of 'waited short time' and the WAIT_TIME of -1 show that this
> is not waiting.
>
> The values of WAIT_TIME are :
>
> Negative : the wait time was unknown.
> Zero : the session is still waiting.
> Positive : the actual time waited.
>
> PLUS for a session that is waiting, the STATE will be 'WAITING'.
>
> You have to take STATE, WAIT_TIME and SECONDS_IN_WAIT together.
>
> A STATE of 'waited short time', as you have, means that the actual wait
> was less than one cent-second and the WAIT_TIME is always shown as -1.
>
> The WAIT_TIME you see is the session's LAST wait time - so whatever
> event it was waiting on previous to the current one would have waited
> nearly 400 seconds. I'd be willing to say that in a batch program it
> would be something like 'SQL*NET message from client' as Oracle has fed
> the batch program a shed load of data which it has to process before
> doing the next lot/query.
>
> Obviously, you'd want to trace the session to be 100% sure ....
>
>
> HTH
>
> Cheers,
> Norman.
>
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