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 <[email protected]> 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 >
