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bug#21949: git-2.6.3: 108M download, but 23M installed
From: |
Ludovic Courtès |
Subject: |
bug#21949: git-2.6.3: 108M download, but 23M installed |
Date: |
Wed, 18 Nov 2015 19:12:43 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Florian Paul Schmidt <address@hidden> skribis:
> I noticed this earlier and wonder if it's a bug or not:
>
> When downloading the git-2.6.3 substitute from hydra it is a hefty
> 108M download, but installed in the store it's just 23M.
The fact that the result is small is due to hard links (under
libexec/git-core), resulting from deduplication performed by the daemon:
--8<---------------cut here---------------start------------->8---
$ du -msc /gnu/store/8xk88mnx31b6i9jz0n7x7zm4xrnknj3b-git-2.6.3
23 /gnu/store/8xk88mnx31b6i9jz0n7x7zm4xrnknj3b-git-2.6.3
23 totalo
$ du -mscl /gnu/store/8xk88mnx31b6i9jz0n7x7zm4xrnknj3b-git-2.6.3
249 /gnu/store/8xk88mnx31b6i9jz0n7x7zm4xrnknj3b-git-2.6.3
249 totalo
--8<---------------cut here---------------end--------------->8---
The problem is that the Nix archive format (Nar) is dumb and doesn’t do
anything sensible with hard links. So the actual archive is indeed that
big:
--8<---------------cut here---------------start------------->8---
$ guix archive --export /gnu/store/8xk88mnx31b6i9jz0n7x7zm4xrnknj3b-git-2.6.3 |
wc -c
259217552
--8<---------------cut here---------------end--------------->8---
Hydra compresses it with bzip2, hence the 108 MiB.
Git is obviously a pathological case. However, the issue is a more
global one that I think we should address using content-addressable
storage:
https://lists.gnu.org/archive/html/guix-devel/2015-03/msg00666.html
Ludo’.