Anyone familiar with the mentioned `bupdate` tool and zsync¹? I'd love to read a comparison, as I've only used the latter.
Flipping quickly through the zsync docs, it looks very well done. I'm not sure if the way they adapted rsync is better or worse than the bup/bupdate way of doing it; it looks like they take more time to do the initial encoding of the index file, but that's not very important since you only do it once, especially if it saves bytes.
They also have a (complex and potentially error-prone) way to look into .gz files and sync them extremely efficiently even without gzip --rsyncable. That's really cool, but risky, and of course only works with gzip, not other compressors. Not sure if that's a good idea or a bad idea, but nobody forces you to use it.
tl;dr zsync has actual documentation and an actual release, so you should probably use it instead of bupdate.
(People should feel free to ask me any questions about redo, bupdate, the redo container builder, etc in the comments here if you like.)
* I've abused webseed support in torrent clients to do similar things - a downloader based on the torrent chunk hashing format would be quite interesting
* rsync can do it, maybe
* http://xdelta.org/ - have used this to patch Raspberry Pi images
FWIW, the last release of `zsync` predates `gzip --rsyncable` by about six years¹.
> People should feel free to ask me any questions
"Thanks" isn't a question, but thanks for creating `redo` and the great articles. I always seem to come out of them having learnt something new, and often end up rabbit holed in the interesting side topics that are raised too.
The zsync docs clearly talk about "gzip --rsync", which I guess must have been an earlier version of "gzip --rsyncable".