Delta packages

[Jan Bramkamp]

On 13.05.2014 22:21, Sean Fagan wrote:
> We have a strong desire to make delta packages -- that is, given version A and version B of a package, to be able to download a package that has only the changes between A and B.
> 
> I've written a little program to create this (it currently only has the files that have changed, not binary diffs, although that would I suppose be possible; just harder).
> 
> I can, I'm sure, come up with a way to manually extract and update the packages databases; however, I'd prefer to do a lot of that in the package code.  (Among other things, being able to specify what the delta is from would be good; I couldn't see a way to add random key/value pairs to the manifest using the pkg* routines, and while I can add it to the +MANIFEST file I create, that doesn't actually do a whole lot.)
> 
> First question:  is anyone working on something like this already?
> 
> Second question:  Any objections to it in principal?
> 
> Merci beaucoup,
> 
> Sean.

It is my understanding that pkgng keeps the old packages in
/var/cache/pkg. Wouldn't it be easier to implement delta packages as
binpatches between the decompressed tar streams of the two package versions?