[pacman-dev] some more delta stats

[Xavier]

On Fri, Mar 6, 2009 at 4:19 PM, Xavier <shiningxc at gmail.com> wrote:
> On Fri, Mar 6, 2009 at 3:38 PM, Nagy Gabor <ngaba at bibl.u-szeged.hu> wrote:
>> Well, these results are cool. If deltas finally work perfectly in alpm we
>> may want to factorize (move) it to a stand-alone xdelta client-server(?)
>> stuff, which is something similar to rsync (but we need a vcs-like stuff
>> here). Well, I know this idea is very ambitious, but I have the impression
>> that we (== Nathan and Xavier:) did something, from which the whole open
>> source community could profit. (Moreover, our alpm code would be cleaner :)
>> At least I didn't find anything which is similar to our low-bandwidth
>> delta-based "vcs system" on the net.
>
> There would be a huge drawback with this idea, that we couldn't simply
> re-use all the existing http/ftp mirrors.
>
> However, I considered writing standalone apps in python :
>
> 1) delta-add.py : analog of repo-add but for delta.
> delta-add delta-database foo1.delta foo2.delta ...
>
> 2) delta-download.py :
> have a delta.conf file, analog to pacman.conf, to specify delta mirrors
> delta-download url : either use deltas from the delta mirrors to
> generate the wanted package, or download the url directly
>
> I was motivated by this solution, when I realized that the repository
> system implemented by pacman is quite nice :
> * pacman.conf specifying for each repo multiple possible urls (mirroring system)
> * refresh only when needed using .lastupdate
>
> So that I would have to reimplement / duplicate this system.
> Also by moving this to an external app, it means the refreshing of the
> database has to be made for each download (for each download, the
> external client app has to be called).
>
> So I lost my motivation and this project didn't go far.
>

Hm I felt by chance on this : http://tonelli.sns.it/pub/mennucc1/debdelta/README
It might be worth looking more in details how it works.