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From <de...@segel.com>
Subject RE: Repairing a corrupted database with invalid checksum on page
Date Mon, 15 Jun 2009 14:14:47 GMT

I would be hesitant in trying to make a 'solution' out of this fix.
For those IBMers who work in the lab, if they are heritage Informix support
people, this would be akin to making tbzero available to the general public.
(If you work in the 'Lab' but don't know what tbzero is, find someone who is
Informix Heritage...) I don't know if tbzero exists today, although because
7.3x exists, I think it still does. To those that don't work for IBM or
worked for Informix, it was a tool used by the support team to clean up a
similar nasty problem, hence the reason I mentioned it. The lesson learned
is that you don't want to allow a dangerous tool out in the open. 

I do agree that what David found was/is a problem. You have to consider that
if you're going to introduce a fix, you need to look at it from a systems or
overall architecture point of view.

I would suggest considering the creation of a recovery mode where the user
has access to a simple interface (or command line) and the process is more
automated and logged.

A corrupted index page? Ok that's easy to fix. A corrupted database page?
Not so easy to fix. You'll have a loss of data and you'll need to compare
the table with one from a previous back up and hope you can get back the

There's more to this problem and its not an *easy* fix. One would hope that
Sun/Oracle would still be supporting javaDB and Derby in the same manner
they support it today and work on strengthening Derby's resilience.



> -----Original Message-----
> From: David Sitsky [mailto:sits@nuix.com]
> Sent: Monday, June 15, 2009 12:11 AM
> To: Derby Discussion
> Subject: Re: Repairing a corrupted database with invalid checksum on page
> > Thank you for posting your solution.  I added a reference to this thread
> in:
> > https://issues.apache.org/jira/browse/DERBY-1648
> >
> > Perhaps you could post your patch there and hit the grant to apache
> button
> > in case someone wants to use it as the basis for an integrated solution.
> Done.
> --
> Cheers,
> David
> Nuix Pty Ltd
> Suite 79, 89 Jones St, Ultimo NSW 2007, Australia    Ph: +61 2 9280 0699
> Web: http://www.nuix.com                            Fax: +61 2 9212 6902

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