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Re: delta in SVN is reversible or not

From: Daniel Shahaf <d.s_at_daniel.shahaf.name>
Date: Thu, 14 Mar 2013 02:03:54 +0200

Branko Čibej wrote on Thu, Mar 14, 2013 at 00:43:24 +0100:
> On 14.03.2013 00:07, Bo Chen wrote:
> > Can anyone help me make clear this question? In SVN, if I have two
> > versions A and B. I compute a delta of B against A, i.e., I can
> > recover B by A and this delta. My question is, can I recover A by
> > using B and the same delta?
>
> No. It's theoretically possible to reverse a delta, but to do that, you
> must have both A and B available.

If you have A and B, you can just do (A-B) to get a reversed delta.

Or maybe you mean that (A-B) can be computed more efficiently given
(A,B,B-A) than given (A,B)?

> This is because the representation of
> the delta between A and B does not show content that was removed, only
> content that was copied from a and new content added to B.
>
> -- Brane
>
>
> --
> Branko Čibej
> Director of Subversion | WANdisco | www.wandisco.com
>
Received on 2013-03-14 01:04:30 CET

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