Re: transaction tables consistent reads - undo records applied

From: Steve Howard <stevedhoward_at_gmail.com>
Date: Sat, 26 Jun 2010 06:02:29 -0700 (PDT)
Message-ID: <f8608dee-55df-4220-8eef-28aa7dcd648f_at_5g2000yqz.googlegroups.com>

On Jun 25, 12:01 pm, joel garry <joel-ga..._at_home.com> wrote:
> On Jun 24, 7:25 pm, Steve Howard <stevedhow..._at_gmail.com> wrote:
>
>
>
> > On Jun 24, 10:20 pm, Steve Howard <stevedhow..._at_gmail.com> wrote:
>
> > > Hi All,
>
> > > 10.2.0.4 three node cluster EE on SLES 10
>
> > ...I should also mention the explain plan for the query is OK.  It is
> > a range scan for the time period being retrieved, which may be two or
> > three hours, representing 300,000 rows (out of 300 million).
>
> > Also, when I look at "table fetch by rowid" for the querying session,
> > it will periodically just stall.  It is as if the session is reading
> > thousands upon thousands of undo blocks for that next row.  The
> > arraysize is 15 (standard SQL*Plus)
>
> > Sometimes this happens, sometimes it doesn't.
>
> > We did apply patch 7527908
>
> I have no idea, but I speculate you can use Tanel Poders' latchprofx
> and poke around on his site about in memory undo to figure this out.
> Does your plan show lots of recursion?
>
> jg
> --
> _at_home.com is bogus.http://www.businessweek.com/news/2010-06-25/oracle-rises-after-sun-ac...

Hi Joel,

I got a tip from Dion Cho regarding this that was also suggesting dc_rollbacks as latching issue, but I could never prove any similarity between his test case and our situation.

http://dioncho.wordpress.com/2009/04/04/rethinking-on-ora-01555-error/

Thanks,

Steve Received on Sat Jun 26 2010 - 08:02:29 CDT