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Re: RMAN internal`s mechanism

From: Ofer Razon <orazon_at_dbnet.co.il>
Date: 3 Mar 2004 09:34:09 -0800
Message-ID: <74c5bf11.0403030934.4bf11310@posting.google.com>


> 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.

Thanks.
Do you know about any existing piece of code that scans the datafiles and process them?

I`m trying to find a solution to synchronize two copies of a datafile : One is older than the other at about a week. The synchronization must be very effective and must do as less writes at the target as it can.
My current solution is to open both of the files as binary files, go block by block (I set the block size) and compare the data. Only if the data read is different - I update the block at the target with the data from the source.
The issue is that this solution must go and read both of the files. I`m looking for a way to make it work better....

Thanks,
Ofer. Received on Wed Mar 03 2004 - 11:34:09 CST

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