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

From: Walker, Jed S <Jed_Walker_at_cable.comcast.com>
Date: Fri, 7 Jun 2013 17:17:44 +0000
Message-ID: <BAA6E28B6241F046AED1E62D8697516C6F6C27FF_at_COPDCEXMB08.cable.comcast.com>

If the customer doesn't have AWR (due to licensing) is there any way to get this over snapshots of time other than doing it yourself? From: Walker, Jed S
Sent: Friday, June 07, 2013 11:16 AM
To: 'Tanel Poder'
Cc: oracle-l_at_freelists.org
Subject: RE: v$sql.disk_reads versus v$sql.physical_read_requests

Ah, of course, thank you!

From: tanel_at_poderc.com [mailto:tanel_at_poderc.com] On Behalf Of Tanel Poder Sent: Friday, June 07, 2013 11:10 AM
To: Tanel Poder
Cc: Walker, Jed S; oracle-l_at_freelists.org Subject: Re: v$sql.disk_reads versus v$sql.physical_read_requests

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

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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 8:08 PM, Tanel Poder <tanel_at_tanelpoder.com<mailto: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

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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<mailto: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

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http://www.freelists.org/webpage/oracle-l Received on Fri Jun 07 2013 - 19:17:44 CEST