Re: [PATCH] diff-delta: produce optimal pack data

> On Fri, 24 Feb 2006, Carl Baldwin wrote:
> 
> > Junio,
> > 
> > This message came to me at exactly the right time.  Yesterday I was
> > exploring using git as the content storage back-end for some binary
> > files.  Up until now I've only used it for software projects.
> > 
> > I found the largest RCS file that we had in our current back-end.  It
> > contained twelve versions of a binary file.  Each version averaged about
> > 20 MB.  The ,v file from RCS was about 250MB.  I did some experiments on
> > these binary files.
> > 
> > First, gzip consistantly is able to compress these files to about 10%
> > their original size.  So, they are quite inflated.  Second, xdelta would
> > produce a delta between two neighboring revisions of about 2.5MB in size
> > that would compress down to about 2MB.  (about the same size as the next
> > revision compressed without deltification so packing is ineffective
> > here).
> > 
> > I added these 12 revisions to several version control back-ends
> > including subversion and git.  Git produced a much smaller repository
> > size than the others simply due to the compression that it applies to
> > objects.  It also was at least as fast as the others.
> > 
> > The problem came when I tried to clone this repository.
> > git-pack-objects chewed on these 12 revisions for over an hour before I
> > finally interrupted it.  As far as I could tell, it hadn't made much
> > progress.
> 
> I must ask if you had applied my latest delta patches?
> 
> Also did you use a recent version of git that implements pack data 
> reuse?
> 
> 
> Nicolas
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