On Thu, 2018-11-22 at 11:31 -0500, Josh Boyer wrote:
I'm concerned that this will effectively render EL RPM unable to
handle any Fedora RPMs at all. That's both a practical concern, as
many people develop Fedora using EL and vice versa, and also a broader
ecosystem concern. I would very much like for all of our
distributions to be able to more easily operate together, and this
effectively forks Fedora off into it's own space yet again.
For what very little it's worth, a zchunked rpm is still a valid zchunk
file, and you would be able to easily extract the payload and the
header from a zchunked rpm on an EL system. In fact, because we're not
planning to change the rpm header format at all, there could easily be
a tool to convert a zchunked rpm into an xz or gzipped rpm (and vice
versa). Having said that, there's a huge difference between this and
having EL's RPM actually be able to read Fedora's RPMs.
Have we really looked at the wider scope of what a format change
like
this would do in the context of some of the larger picture things
we're working on with lifecycle and cross-distro collaboration
efforts? I agree this would be better than delta RPMs when looking at
that *specific* usecase, but improving that (even with compose time
benefits) by doing a format change seems to be inflicting a very high
cost for what is an important but relatively small usecase.
This is a really good point and I don't know know the answer. As per
Neal's suggestion earlier in the thread, I posted this to the rpm-
ecosystem mailing list. Michael from SUSE brought up some very valid
concerns about how well zchunk would compare with deltarpm in delta
efficiency, but apart from that, it's been pretty quiet there.
If it's already obvious that the cost for this proposal isn't worth the
gain, I do completely understand. If we're not sure, I'll do a proof-
of-concept that converts standard rpms into zchunked rpms, so we can
compare sizes and deltas, and hopefully get some data points on speed.
Jonathan