From: C. Scott Ananian <cscott@cscott.net>
Date: Tue, 03 May 2005 15:50:59 GMT
Subject: Re: RFC: adding xdelta compression to git
Message-ID: <Pine.LNX.4.61.0505031146130.32767@cag.csail.mit.edu>
In-Reply-To: <Pine.LNX.4.58.0505022131380.3594@ppc970.osdl.org>

On Mon, 2 May 2005, Linus Torvalds wrote:

>> * Changes the repository format.
>
> It wouldn't necessarily. You should be able to do this with _zero_ changes
> to existing objects what-so-ever.

Yes.  The 'chunking' code I posted earlier does this, etc.  It's kinda odd 
computing a SHA-1 including the 'blob <size>\0' header, even when your 
representation doesn't use this type exactly, but it's no big deal.  I'm 
still tinkering with this, btw; I can get modest improvements in 'real' disk 
space used, but nothing earth-shattering (yet).  I'll post the list of 
things I tried and how well they worked at some point, just to save people 
the effort of retrying things.

I've been working from the 'no knowledge of commit structure needed' 
perspective; I think Chris Mason has been using the structure of the 
commit object to guide delta-fication and showing more impressive 
space savings.
  --scott

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