Re: Physical Read Waits less than Physical Reads
- From: Dion Cho <ukja.dion@xxxxxxxxx>
- To: charlottejanehammond@xxxxxxxxx
- Date: Wed, 10 Nov 2010 09:52:55 +0900
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".
================================
Dion Cho - Oracle Performance Storyteller
http://dioncho.wordpress.com (english)
http://ukja.tistory.com (korean)
http://sites.google.com/site/otpack (tpack)
================================
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
>
>
>
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
Other related posts:
