[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Popularity of bzr-builddeb and dh-make

On Thu, Oct 18, 2012 at 08:16:50PM -0700, Russ Allbery wrote:
> Steve Langasek <vorlon@debian.org> writes:

> > The last time I complained about non-pristine-tar git package repos on
> > IRC, I was told that pristine-tar doesn't scale.  So apparently in git
> > usage, folks haven't worked out that the unpacked upstream source should
> > be tracked as a branch instead of trying to track a pristine-tar delta
> > against the upstream git branch directly.

> What did you mean by that last sentence?  I was unable to parse it.  In
> particular, I think I don't understand the difference between "tracked as
> a branch" and "track a pristine-tar delta against the upstream git
> branch," which both sound like they mean the same thing.

The UDD branch model used in Launchpad has three branches (not counting the
pristine-tar objects):

 - the upstream branch (as it exists upstream)
 - a synthesized branch which merges from the upstream branch and tracks
   the contents of the upstream tarball releases /as contents/
 - the packaging branch

AIUI, most users of pristine-tar in git don't have the second of these
branches, which means the pristine-tar binary delta is done against the
upstream branch - so each pristine-tar blob contains all the information
about autogenerated files in the tarball, in a format that doesn't in turn
compress well in the git repository.  And if your packaging branch actually
tracks the full source package contents, then it would have to track the
autogenerated files, so you might actually be storing these files twice.

In UDD, the delta to the autogenerated files from one upstream release to
the next is stored like any other branch delta, and the pristine-tar blob
only has to account for the tarball/gzip metadata itself.  I believe this
was done by design precisely in order to address the pristine-tar
scalability problem; in any case, I don't hear complaints about pristine-tar
being unusable for Ubuntu packages for the reasons people seem to be
shunning it for Debian packages in git.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek@ubuntu.com                                     vorlon@debian.org

Attachment: signature.asc
Description: Digital signature

Reply to: