Re: wishlist: “repack” generations history of profile

[zimoun]

Hi Liliana,

On Sat, 21 May 2022 at 13:30, Liliana Marie Prikler <liliana.prikler@gmail.com> 
wrote:

> I think we should implement this as a single --keep=stuff operator,

[...]

> I'm not so sure if I understand the generation bit correctly, but with
> the switch proposed above, you'd --keep=generations, which keeps just
> enough data to make switch-generation work "lazily".

>From my understanding, this operator would add complexity and I am not
convinced that being so fine-grained is necessary.

Basically, the workflow is:

        guix package -m foo.scm
        guix package -m bar.scm
        guix pull
        guix package -m baz.scm
        guix gc -d 3m
        guix pull
        guix package -m bong.scm

and “guix gc” potentially remove all of the generation “foo.scm” (say
generation 1).  Instead, I would like to remove the content only to save
space but keep the meta (basically the internal manifest).  This way,
the store would not fully contain the items but it would be possible to
have,

        guix package --switch-generation=1

rebuilding the missing items for the generation 1.

Today, it is not possible to keep the history of generations and delete
the store items of old generations.  I am proposing to have an option
for “guix gc” allowing that: keep the history and the ability to switch
and in the same time remove the old items.


Cheers,
simon