Upgrading to new Ubuntu releases (Re: Announcing Beta release of Ubuntu 6.06 LTS)

[Matt Zimmerman]

On Fri, Apr 21, 2006 at 05:34:45PM +0100, Antony Gelberg wrote:
> Matt Zimmerman wrote:
> >Sure, more information can be found here:
> >https://launchpad.net/distros/ubuntu/+spec/release-upgrades
> 
> Thanks.
> 
> >"apt-get dist-upgrade" has never truly been sufficient, and this tool is a
> >solution to that problem, not its source.  Upgrading to a new Ubuntu 
> >release
> >is a complex high-level operation which is not easily addressed with the
> >kinds of heuristics used to support incremental upgrades.
> 
> Any comment on the suitability of aptitude versus apt-get for the purpose?

aptitude has a somewhat different implementation, but faces the same basic
difficulty in that it only has a sea of dependency relationships to work
with, and no high-level guidance about the goal it is trying to achieve.
To apt and aptitude, all packages look alike, and it tries to decide
heuristically which packages are important, and make upgrade decisions
based on those guesses.

Have you ever seen apt-get dist-upgrade remove the ubuntu-desktop package
unexpectedly?  That's an example of a scenario where this approach results
in a poor upgrade solution.

> >The availability of a GUI tool should not have any impact on users who
> >choose not to use it.  You may still perform upgrades using the
> >command-line tools, and resolve any difficulties manually, just as you
> >always have.
> >
> >But for those who want it to "just work", there is now a more suitable
> >option.  It is a complementary use case.
> 
> Understood, I think.  I just hope that difficulties won't arise from
> developers not correcting known problems that would arise with aptitude
> but not with the new tool.  I think you are saying that both methods are
> supported, just that one method is less interactive, in which case all is
> well.

That's mostly accurate, though the new method is more functional and
complete.  So while both methods are supported, there are upgrade problems
which are fundamentally difficult to solve with the traditional approach.

For example, users upgrading from Hoary to Breezy would typically end up
with both OpenOffice.org version 1 and version 2 installed, which is almost
never what the user wanted or expected.  The new upgrade tool understands
this type of situation, and would know that when upgrading to the new
release, openoffice.org2 was meant to supersede openoffice.org, and provide
corresponding hints to apt so that it does the right thing.

Make sense?

-- 
 - mdz