Re: binary differencing algorithm

On Sep 4, 2005, at 4:18 AM, Michael Bartholomäus wrote:

> Hi again,
>
> still I am a student of computer science writing my diploma thesis
> about
> "revision control of XML data in the context of a CMS".
>
> Are there any citable (scientific?) publications about the
> binary differencing algorithm (vdelta?) Subversion uses?
>

Subversion 1.0 and 1.1 use the vdelta algorithm to produce binary diffs.

Subversion 1.2 and later use the xdelta algorithm to produce binary
diffs.

Both of the algorithms are public, published papers. Just google for
them.

Subversion uses a single format called 'svndiff' to represent the
binary diffs; both algorithms produce svndiff data, and thus
decompression happens no matter what. Vdelta and Xdelta simply
generate the svndiff data in the first place. So, if you have a
repository that started out with svn 1.0 or 1.1, and has since
upgraded to svn 1.2, it likely contains a mixture of svndiff data
generated by both algorithms.

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