Re: effectiveness of rsync and apt

[Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>]

Peter Samuelson <peter@p12n.org> writes:

>> * Goswin von Brederlow:
>> > Look at zsync and help develope it far enough so it can look into
>> > debs. Without that the gain is practicaly 0 or less.
>
> The other thing to do would be to lobby for dpkg-deb and dpkg-source to
> use 'gzip --rsyncable' when building stuff.  (That, or sneak
> "--rsyncable" into $GZIP inside buildd and pbuilder environments
> everywhere.)
>
> [Florian Weimer]
>> The downside is that anything that doesn't work on entire .debs is
>> very likely to change them at the byte stream level (you only need to
>> use slightly different zlib versions or parameters).
>
> Yeah, that's the weakness of the zsync idea.  Fortunately for them,
> zlib uses a very mature algorithm so it doesn't change often.

You can also check the checksum of the compressed blocks to detect
when rebuilding the deb fails and then just get it compressed.

MfG
        Goswin