[Rpm-ecosystem] Some points about zchunk

[Neal Gompa]

On Thu, Jul 12, 2018 at 3:27 PM Jonathan Dieter <jdieter at gmail.com> wrote:
>
> On Wed, 2018-07-11 at 07:55 -0400, Neal Gompa wrote:
> > On Wed, Jul 11, 2018 at 7:30 AM Michael Schroeder <mls at suse.de> wrote:
> > >
> > > On Wed, Jul 11, 2018 at 12:23:47PM +0100, Jonathan Dieter wrote:
> > > > That's something I didn't think of, and you're absolutely right.
> > > >
> > > > So, to summarize, we'll leave the gzip entry as "primary", so legacy
> > > > systems will still download without any problems, and create a new
> > > > "primary at zchunk" that librepo will automagically download if zchunk is
> > > > supported?
> > >
> > > I think there should be some librepo option to enable this. Be it
> > > something boolean or a fancy string list that can be used for
> > > some future compression method.
> > >
> > > But I'm just one person. Can someone else on this list please speak
> > > up and tell us if we want to do something stupid or not? Maybe the
> > > librepo maintainer? Or the libdnf maintainer? Anybody?
> > >
> >
> > While I agree that we should have an attribute that declares the
> > compression format for fetching, I wonder how legacy clients would
> > handle it? There must be a reason why we haven't done it so far after
> > going from gzip to bzip2 to lzma to xz?
> >
> > It's not unprecedented for there to be stuff like this (we handle the
> > sqlite data variant with <foo>_db). We could, for consistency, do
> > "<foo>_zckxml" and have librepo fetch that when it's available.
>
> I'd go with <foo>_zck since <foo> is, by default, xml, but, other than
> that, I think what you (and Michael) are suggesting makes sense.
>
> Michael, I agree that there should be some way to manually enable
> zchunk (with a method that will work with future algorithms) in
> librepo.
>
> I don't mind writing the code, but I'd like to hear some consensus on
> the method and element name.

I'm okay with this, but does this mean we could also have (cheaply)
zck of arbitrary xml files appended using tools like modifyrepo_c,
then?



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