Re: Physical Read Waits less than Physical Reads

Hi, Charlotte.

1. One "db file scattered read" wait would mean physical reads of several
blocks, aka multi block I/O.

2. Direct path read would also be recorded as "physical reads".

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On Wed, Nov 10, 2010 at 4:25 AM, Charlotte Hammond <
charlottejanehammond@xxxxxxxxx> wrote:

> Hi All,
>
>
> For some of my sessions I see, for example:
>
>
> V$SESS_IO shows 200,000 physical  reads
>
> V$SESSION_EVENT shows < 100,000  total waits for “db file * read”  (and
> “read by
> other session”)  etc.
>
> Does that mean half my physical  reads didn’t wait at all?  How is that
> possible?  (I see this under high load - under low load number of reads is
> approximately the same as the number of waits for the same SQL)
>
>
> I'd be very grateful if you could explain this observation to me! (Platform
> is
> 10g on AIX)
>
> Thank you!
>
> Charlotte
>
>
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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