Re: [Gnu-arch-users] Re: arch with 'special files'

[Jan Hudec]

On Tue, Apr 05, 2005 at 18:17:05 +0100, Andrew Suffield wrote:
> On Tue, Apr 05, 2005 at 03:34:25PM +0200, Jan Hudec wrote:
> > > Inexact patching for jpeg images anyone? Or for (ugh!) XML RSS files[1]? 
> > > Or...
> > 
> > I believe there is some kind of xml-diff, that compares the trees, not
> > the text ;-). One such is built into openoffice...
> 
> Yes, but there's no corresponding patch tool, nor can there be (any
> more than there can for xdelta), since XML is semantically null and
> syntactically useless.

Even if there is a problem with generic XML, because it may have
arbitrary semantics, it is certainly possible to have a patch tool for
formats built on XML that do have specific semantics, eg. the OpenOffice
documents.

> > And even if it's not inexact patching, instead of two versions, you can
> > store one version and a difference. And knowing the nature of the data
> > can make this more efficient.
> 
> Delta compression is a fairly trivial storage optimisation that's not
> particularly interesting. The archive isn't your problem for storage
> anyway; it is the smallest thing in arch.

If the archive stores mostly Word documents, it certainly does make
a difference.

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                                                 Jan 'Bulb' Hudec 
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