Issue
I have been wondering over the past week, why software package updates for linux and Ubuntu in particular, using the APT package repository system, do not take advantage of the benefits of rsync, especially considering the size of some update packages.
Is there a technical problem with implementing this, or do I need to start research/coding for the benefit of all humanity?
Solution
The reason that these distributions use packages is that you can nicely encode the installation requirements, and scripts to be run at installation, modifications to be made etc. in a well-defined packet format.
Now, what you're asking for is
why don't apt and the like offer incremental updates?
They do. Yum calls these delta RPMs, and apt-distros have debdelta.
EDIT: By the way, I find these to be rather ill-suited for the average broadband access that doesn't pay per MB: Even using my SSD, a 2MB/s downlink gets most packages faster completely compared to first determining the local state, downloading a delta package and then rebuilding the full update locally, not even counting the additional processing power needed at the remote repository. If you're on mobile access, however, that feature is awesome.
Answered By - Marcus Müller