Re: v$sql.disk_reads versus v$sql.physical_read_requests

From: Tanel Poder <tanel_at_tanelpoder.com>
Date: Fri, 7 Jun 2013 20:09:36 +0300
Message-ID: <CAMHX9JKLSXsFBti81xBbFign8+=L206k0FMqCFBCGaJwSb2QkQ_at_mail.gmail.com>

the same goes for the "physical read IO requests" and "physical reads" statistics in v$sesstat/v$sysstat....

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On Fri, Jun 7, 2013 at 8:08 PM, Tanel Poder <tanel_at_tanelpoder.com> wrote:



> disk_reads is number of blocks read

> physical_read_requests is the number of IO requests done

>

> so if all you do is single block reads, the disk_reads =

> physical_read_requests

>

> but if you also do multiblock reads, then the dist_reads should be bigger

>

> --

> *Tanel Poder*

> Enkitec (The Exadata Experts)

> Training <http://blog.tanelpoder.com/seminar/> | Troubleshooting<http://blog.tanelpoder.com/>

>  | Exadata<http://www.amazon.com/Expert-Oracle-Exadata-Apress/dp/1430233923>

>  | Voicee App <http://voic.ee/>

>

>

>

> On Fri, Jun 7, 2013 at 8:03 PM, Walker, Jed S <

> Jed_Walker_at_cable.comcast.com> wrote:

>

>> I was looking over v$sql and noticed it has disk_reads and

>> physical_read_requests. I couldn't tell from the docs exactly what the

>> difference is.

>> I'm guessing disk_reads is the number of disk reads requested, and

>> physical_read_requests is how many reads were actually required from the

>> disk (maybe because of diffs in db block size and disk block size?)

>> Curious if anyone knows for certain?

>>

>> thanks

>>

>> --

>> http://www.freelists.org/webpage/oracle-l

>>

>>

>>

>



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Received on Fri Jun 07 2013 - 19:09:36 CEST