Re: Compress VCS checkouts?

[Eric Bavier <ericbavier@centurylink.net>]

On Mon, 05 Feb 2018 11:27:10 +0100
ludo@gnu.org (Ludovic Courtès) wrote:

> Hello!
> 
> Eric Bavier <ericbavier@centurylink.net> skribis:
> 
> > A while back I toyed with the idea of a "Sources DVD" for Guix, much
> > like Trisquel has. While looking into the feasability of this, I
> > noticed that the git/svn/cvs/hg checkouts our packages use are not
> > compressed in the store.  So I wrote a simple script to compare the raw
> > size of all source checkouts with their corresponding xz-compressed
> > tarballs.  
> >
> > At the time, I couldn't convince myself the trouble was worth the
> > effort; we had only 385MiB of uncompressed source checkouts, which
> > would compress to 135MiB.
> >
> > Since that initial investigation, the number of packages using VCS
> > checkouts has risen from 50 to 389, and the on-disk size of that source
> > has risen to 3784MiB uncompressed.  We could compress that down to
> > 538MiB.
> >
> > Compression in not free, but I think it would be nice for our build
> > servers who have to store and serve (which, iirc, requires them to
> > compress it anyhow) this source.  
> 
> ‘guix publish -C’ always compresses store items, unless they are regular
> files ending in “.gz”, “.xz”, etc.  So there’s no problem here.

I see, ok.

> 
> It seems to me that the only benefit of compressing checkouts would be
> the use case you’re talking about.  For everyday use, it’s actually more
> efficient to leave the uncompressed, so that people don’t end up doing
> round of compression/decompression when they run “guix build”.

Often, people would end up fetching the compressed source from a
substitute server, no?  And currently I already need to uncompress
what I get from a substitute server before building.

But now I'm wondering why we bother with the "repack" portion of
"patch-and-repack"?

> That said, at worst, this could be addressed by writing a specific tool
> for the job.

Yes. I was hoping it could be avoided though.

In the meantime I can continue to monitor the situation.

`~Eric