Re: rollback and redo questions

I understand this subject much better due to your excellent postings. One more question. I'm just wondering about the order of redo,datafile,and rollback.
In which order does this writting take place? If we are updating blocks 1-25 in your
example, is this written to redo, then after the checkpoint, to the datafile and rollback
simutaneously? Or is it written to redo, & rollback simutaneously, and then to the datafiles
at checkpoint? Etc., Just curious.

Thomas Kyte wrote:

> A copy of this was sent to "B.Sc Yassir Khogaly"
> <yassir_at_khogaly.freeserve.co.uk>
> (if that email address didn't require changing)
> On Wed, 4 Nov 1998 15:20:50 -0000, you wrote:
>
> >I've a small comment about your comment "It'll actually roll forward from
> >redo first ( recovering the rollback segements
> >>as well -- they are part of the redo information, they are logged) and then
> >>rollback any uncommitted transactions from the rollback segements (which
> >just
> >>got recovered themselves).
> > This should be "It'll actually roll forward from redo entries recovering
> >the rollback segements are part of the Recovery Process
> >because the rollback segments are actually part of the redo/redo information
> >nesessary for Recovery.
> >
>
> ????
>
> thats what I said in different words -- we said almot the same thing. Your way
> of saying it actually sounds more ambigous to me.
>
> You say "recovering the rollback segments are part of the recovery process" --
> are you saying that recovering the rollback segements is part of the recovery
> process (yes it is) or are you saying that rollback segments are part of the
> recovery process (yes they are).
>
> I basically said:
>
> - roll forward from redo first (and by the way, rollback segments are recovered
> as well -- they are logged)
>
> - then rollback any uncommitted transactions from rollback (which just got
> recovered).
>
> >>It'll actually roll forward from redo first ( recovering the rollback
> >segements
> >>as well -- they are part of the redo information, they are logged) and then
> >>rollback any uncommitted transactions from the rollback segements (which
> >just
> >>got recovered themselves).
>
>
> Thomas Kyte
> tkyte_at_us.oracle.com
> Oracle Government
> Herndon VA
>
> --
> http://govt.us.oracle.com/ -- downloadable utilities
>
> ----------------------------------------------------------------------------
> Opinions are mine and do not necessarily reflect those of Oracle Corporation
>
> Anti-Anti Spam Msg: if you want an answer emailed to you,
> you have to make it easy to get email to you. Any bounced
> email will be treated the same way i treat SPAM-- I delete it.
Received on Tue Nov 10 1998 - 08:56:30 CST