[Aptitude-devel] Bug#570377: Bug#570377: aptitude chooses to remove packages instead of upgrading

[Vincent Lefevre]

On 2014-02-04 10:49:53 +0800, Daniel Hartwig wrote:
> On 4 February 2014 10:24, Vincent Lefevre <vincent at vinc17.net> wrote:
> > Because I would say: A remove can be caused by some obsolete package
> > due to a conflict with the newly installed package (or one of its
> > dependencies). But in such a case, the remove would occur in *every*
> > solution. If a package is not obsolete, aptitude should never propose
> > it for removal when another solution can solve the problem.
> >
> 
> That is not the results from the current problem resolver, removals
> often pop up in isolated solutions, including different solutions with
> different removals.  I do not know why that happens, however, given
> that it does, the proposed change to safety levels will dismiss some
> potentially trivial, very short solutions (e.g. 1 removal) in favour
> of dozens or more solutions that install/upgrade hundreds of packages
> each.

But removing a package providing a useful application is not a
satisfactory solution. And having to upgrade hundreds of packages
(which is quite rare) is not a problem since this is what users
should eventually do, for various reasons (security...). So, the
size of the solution is not a good criterion.

> Again, I am only addressing the proposed patch.  There are better
> options, such as adjusting the default value of
> Aptitude::ProblemResolver::SolutionCost to account for the number of
> removals vs installs, or similar, but people should use such settings
> and provide feedback on the quality of the solutions and their order.

It would be better if aptitude could tell the reasons that led to the
proposed solution.

-- 
Vincent Lefèvre <vincent at vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)