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Re: RMAN internal`s mechanism

From: Connor McDonald <hamcdc_at_yahoo.co.uk>
Date: Wed, 03 Mar 2004 20:57:02 +0800
Message-ID: <4045D61E.4BDE@yahoo.co.uk>


Jonathan Lewis wrote:
>
> Notes in-line
>
> --
> Regards
>
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
> The Co-operative Oracle Users' FAQ
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
> March 2004 Hotsos Symposium - The Burden of Proof
> Dynamic Sampling - an investigation
> March 2004 Charlotte OUG (www.cltoug.org) CBO Tutorial
> April 2004 Iceland
> June 2004 UK - Optimising Oracle Seminar
>
> "Ofer Razon" <orazon_at_dbnet.co.il> wrote in message
> news:74c5bf11.0403030230.1464f170_at_posting.google.com...
> > Hi all.
> >
> > As far as I know, RMAN is capable to backup only the blocks that
> > changed since it`s last backup.
> > I`m really interested in the mechanism used by RMAN to detect these
> > blocks when it runs.
> > Does anyone here know how is it implemented?
> >
>
> Every block has a last change number - which is the SCN
> at the last change plus a counter that goes from 1 to 254.
> rman knows when the SCN when it last did a backup, reads
> each block, and checks the last change number.
>
> > My goal is to use the same mechanism to find which blocks were changed
> > since the last check.
> >
>
> Possible - so long as you knew the SCN when rman started (or perhaps
> when it started each file, or tablespace - that's a little detail that I'm
> not
> so sure on; the file would be the obvious choice). The last change SCN
> is in a fixed location in the block, so you could write some 3GL code to
> scan each file and pick it out from each block. I am curious to know why
> you want to do this.
>
> > Ofer.

Has anyone played with the block change tracking in 10G - is the tracking information revealed/accessible... (I suspect not)

Cheers
Connor

-- 
-------------------------------
Connor McDonald
http://www.oracledba.co.uk
Co-Author: "Mastering Oracle PL/SQL - Practical Solutions"
Received on Wed Mar 03 2004 - 06:57:02 CST

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