Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.misc -> Re: Which RBS is my Update using ?

Re: Which RBS is my Update using ?

From: Daniel Morgan <dmorgan_at_exesolutions.com>
Date: Mon, 23 Sep 2002 21:44:31 GMT
Message-ID: <3D8F8B35.339D051C@exesolutions.com>


Paul Brewer wrote:

> "Daniel Morgan" <dmorgan_at_exesolutions.com> wrote in message
> news:3D8E4E10.8AAABEFC_at_exesolutions.com...
> > Paul Brewer wrote:
> >
> > > "Daniel Morgan" <dmorgan_at_exesolutions.com> wrote in message
> > > news:3D88D674.1619D215_at_exesolutions.com...
> > > > Tanel Poder wrote:
> > > >
> > > > > Hello,
> > > > >
> > > > > > What you are missing ... is that rollback segments need to be able
> to
> > > expand to
> > > > > > handle the largest transaction on the system. That is not the same
> as
> > > saying they
> > > > > > need to permanently be large enough to handle the largest
> transaction
> > > on the
> > > > > > system.
> > > > >
> > > > > I still don't see why rollback segments in my configuration are less
> > > > > expandable than "They should all be identical and sized to handle
> the
> > > > > largest transaction on the system" configuration which you posted
> > > > > yesterday..
> > > > >
> > > > > But about the cheap price of disk v.s. administration work cost, I
> agree
> > > > > with you.
> > > > >
> > > > > Thank you for your time,
> > > > > Tanel.
> > > >
> > > > I'm not sure I understand your question. Rollback segments expand. And
> > > expand until
> > > > they either hit the maximum allowed extents parameter or run out of
> disk
> > > space. So as
> > > > long as any rollback segment can expand enough to hold any transaction
> > > which rollback
> > > > segment becomes irrelevant.
> > > >
> > > > If you try to force a transaction into a specific rollback segment.
> And
> > > for any reason
> > > > that specific segment is unavailable. The transaction will fail.
> > > >
> > > > Daniel Morgan
> > > >
> > >
> > > OK, I'll rise to this one.
> > >
> > > Our organisation runs Peoplesoft in Atlanta.
> > > Each morning at 3 a.m. we replicate about 80 of the Peopleshit tables
> back
> > > to the U.K., then sort them out into something like a rational structure
> for
> > > reporting purposes.
> > > So, during the day, the U.K. tables are read only, and we don't need
> much by
> > > way of rollback segments. However, during the actual replication process
> we
> > > need to use a segment ROLL_BIG, so that the entire refresh group will
> either
> > > succeed or fail.
> > >
> > > Paul
> >
> > And your point is? ;-)
> >
> > All I said was make all of your rollback segments capable of expanding to
> be as
> > large as ROLL_BIG. The cost of doing this is zero.
> >
> > Smaller transactions won't ever expand beyond whatever transactions they
> > receive. But if they do end up being the rollback segment chosen for the
> nightly
> > process ... they will not fail. Right now you have a single point of
> failure.
> >
> > Daniel Morgan
> >
> Daniel,

>

> ROLL_BIG is offline during the day. The nightly session brings it online,
> does 'set transaction use rollback segment ROLL_BIG', does its work, then
> takes it offline again.
> The other rollback segments are all equally sized (and much smaller).
> What's wrong with that?
>

> Regards,
> Paul

Nothing until the first time something goes wrong: Then everything.

What's wrong with resizing all of your rollback segments?

Daniel Morgan Received on Mon Sep 23 2002 - 16:44:31 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US