Re: db file sequential/scattered read - physical or logical io or both?
- From: Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>
- To: oracledbawannabe@xxxxxxxxx
- Date: Sun, 13 Jun 2010 23:23:24 -0700
When you run the report via SQL*Plus with autotrace on, (or look at
the session stats) what is the physical reads & consistant gets
numbers? Likely the filesystem cache is providing the "lift" in
performance.
On Sun, Jun 13, 2010 at 3:31 PM, Oracle Dba Wannabe
<oracledbawannabe@xxxxxxxxx> wrote:
> So I have an idle system, where I run a sql report. The report takes an hour
> to run. I look at the awr report (30 min interval), and see the io wait
> events for sequential and scattered reads. The first has an avg wait time of
> 7ms the second 10ms. These waits as I understand it are physical io requests
> - correct? The p1 and p2 parameters point to file and block numbers so I
> guess that makes sense. Anyway I rerun the same report, look at the new awr
> and now see the same wait events, only with much smaller wait times. Which
> means data was read from cache - if that's the case why are the same wait
> events issued? it seems a bit confusing that way.
--
Regards,
Greg Rahn
http://structureddata.org
--
//www.freelists.org/webpage/oracle-l
Other related posts:
