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Re: [PATCH] Replace vdelta with xdelta variant

From: Malcolm Rowe <malcolm-svn-dev_at_farside.org.uk>
Date: Mon, 21 Jan 2008 10:43:13 +0000

On Fri, Jan 18, 2008 at 07:54:59PM +0100, Niels Werensteijn wrote:
> Malcolm Rowe wrote:
>> On Thu, Jan 17, 2008 at 11:49:32PM +0100, Niels Werensteijn wrote:
>> Interesting. This sounds similar to a patch that Dan Berlin (cc'd)
>> produced around the time of the Subversion conference, which used
>> Rabin fingerprinting (basically a CRC) and a match table.
> Is this in the mailinglist archive? If so, please give me a hint where to
> find it? :)

Afraid not. It's on my laptop :-/, and Dan should also have a copy.

Thinking about it a little more, we weren't actually planning on
replacing vdelta -- we were going to replace xdelta, with something
faster and/or better performing.

vdelta-against-empty-stream is essentially just compression, so I wonder
if we can just adapt/use zlib in some way (sorry, been a while since I
looked at this). Though you mentioned that your changes would help if a
large binary file changed significantly -- why's that? (because as far
as I'm aware we need to make a decision about what compression/delta
scheme to use _before_ we see the whole file, which means we can't say
things like 'use xdelta, or just self-compress if that's better'.


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Received on 2008-01-21 11:43:34 CET

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