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.
Received on Wed Mar 03 2004 - 04:55:11 CST
