Hey Allan, well, this works with all compression algorithms. Just the delta patch would be compressed with zstd. But since Pacman would decompress the regular package to a tar and the result is a tar, it doesn't matter which compression algorithm the packages use. Apart from that, the delta patch could be made with any program - zstd is just currently the best option IMHO. xdelta3 patch files take (with the default options) around 10 times longer to be created than zstd patch files – which then are a bit smaller. But xdelta3 uses zlib, so decoding is much slower as well. That's why I used zstd in my experiments instead. Zstd can be however asked to invest more time into compression: With something like '-15' which then usually outperforms xdelta3 patch files in size while still being much faster in terms of decoding – I just don't see the point investing so much CPU time into that. The major change for pacman would be to support a tar based checksum and signature along with the compressed file signature/checksum. And additionally understand which files to fetch to get from version x to y and which program to call to create the tar it needs. Best regards, Ruben On Sun, 8 May 2022 at 09:48, Allan McRae <allan@archlinux.org> wrote:
On 8/5/22 09:10, Ruben Kelevra wrote:
Hey guys,
previously pacman have had a delta update functionality which was (to my understanding) removed because of safety concerns and poor performance.
Since the old delta version was written (and removed) zstd got the ability to create delta patches.
Thanks. However I have little interest tying delta support to a specific compression algorithm.
Allan