hi I recollected my earlier experiments on computing package diffs, and prepared a package called 'debdelta'. It is available at http://tonelli.sns.it/pub/mennucc1/debdelta and also uploaded into experimental.
This package contains both a command 'debdelta', to compute deltas of Debian packages, and a command 'debpatch', to apply them. Given the old file.deb (*) and the correct file.debdelta , 'debpatch' builds the new deb; the new deb is identical to the original new deb. Here are some results debdelta emacs-snapshot-common_1%3a20060512-1_all.deb emacs-snapshot-common_1%3a20060518-1_all.deb /tmp/e.debdelta deb delta is 12.1 % of deb that is, 15528kB would be saved debdelta nautilus-data_2.14.1-2_all.deb nautilus-data_2.14.1-3_all.deb /tmp/n.deb deb delta is 4.5 % of deb that is, 3261kB would be saved debdelta emacs-snapshot-gtk_1%3a20060512-1_i386.deb emacs-snapshot-gtk_1%3a20060518-1_i386.deb /tmp/eg.deb deb delta is 69.8 % of deb that is, 603kB would be saved debdelta openssh-client_1%3a4.3p2-1_i386.deb openssh-client_1%3a4.3p2-2_i386.deb /tmp/o.deb deb delta is 4.6 % of deb that is, 549kB would be saved This is a security upgrade: debdelta mozilla-browser_1.7.8-1sarge3_i386.deb mozilla-browser_1.7.8-1sarge6_i386.deb /tmp/m.debdelta deb delta is 16.3 % of deb that is, 8447kB would be saved Note that it works also on different debs: debdelta kernel-image-2.6.8-2-k7_2.6.8-16sarge1_i386.deb kernel-image-2.6.8-i386/kernel-image-2.6.8-3-k7-smp_2.6.8-16sarge2_i386.deb /tmp/ks.debdelta deb delta is 53.8 % of deb that is, 6819kB would be saved debdelta kernel-image-2.6.8-2-686_2.6.8-16sarge1_i386.deb kernel-image-2.6.8-2-686-smp_2.6.8-16sarge1_i386.deb /tmp/k.debdelta deb delta is 52.3 % of deb that is, 7141kB would be saved As you see, results are good. The best way to use it would be to keep in repository only small deltas; otherwise, the benefit of saving some download time would not outweight the cost of using 'debpatch' (that can take a lot of time on large debs; for example, the last example on kernel takes 30sec on a Athlon64 3000). TODO: - apt support : implement a http-delta method . - change 'debmirror' so that it invokes 'debdelta' before deleting a old file. Anyone want to help ? Other work in progress: - (*) I am working on 'deltas' that may be applied even when the original .deb is not around, but is installed in the host. - support for data.tar.bz2 is half done. Are there any .debs around that use it? - Try different schemes for computing deltas. - Study how tar works, or use jigdo. - recursive deltas... to compute deltas of files that are inside data.tar.gz This would be fantastic for kernel sources a. --- A Mennucc <[EMAIL PROTECTED]> writes: > Brian Eaton wrote: >> Hello all - >> >> Regarding the ideas discussed here: >> >> http://rsync.samba.org/rsync-and-debian/rsync-and-debian.html >> >> Has anyone ever done some log file analysis to figure out how much >> bandwidth would be saved by transferring package deltas instead of >> entire new packages? >>
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