Re: Identical files across subsequent package revisions

["Ludovic Courtès" <ludo@gnu.org>]

Hi!

Miguel Ángel Arruga Vivas <rosen644835@gmail.com> skribis:

> Another idea that might fit well into that kind of protocol---with
> harder impact on the design, and probably with a high cost on the
> runtime---would be the "upgrade" of the deduplication process towards a
> content-based file system as git does[2].  This way the a description of
> the nar contents (size, hash) could trigger the retrieval only of the
> needed files not found in the current store.

Yes, that’s what I had in mind.  :-)

It could go along these lines:

  1. GET /digest/xyz-emacs; the digest contains a list of file/hash
     pairs essentially;

  2. traverse digest and hardlink the files already in /gnu/store/.links
     to the target directory;

  3. pipeline-GET the remaining files and install them.

Like you write, since we already have deduplication, part of it comes
for free.

Ludo’.