Re: .deb format: let's use 0.939, zstd, drop bzip2

[Adam Borowski <kilobyte@angband.pl>]

On Mon, May 13, 2019 at 11:25:11AM +0200, Ansgar wrote:
> On Fri, 2019-05-10 at 16:11 +0200, Adam Borowski wrote:
> > /usr on the box I'm sitting at:
> > * zip the program: dies horribly due to /usr/lib/llvm-7/build/
> > symlink
> >   loops.
> > * zip:
> > 	1891345142 bytes
> > * zip-the-concept (individually compressed files), xz
> > 	1516943024 bytes
> > * tar.xz
> > 	1092591508 bytes
> > 
> > Linux source:
> > * zip:
> > 	213820843 bytes
> > * individually compressed files, xz
> > 	180997203 bytes
> > * tar.xz:
> > 	104318396 bytes
> > 
> > So no, I don't want zip, nor even a randomly accessible format.
> 
> Could you also try 7z?

It uses lzma{,2} thus sizes are about the same; I installed/removed a bunch
of packages in meantime; I'm too lazy to reproduce old test corpus and/or
re-run everything -- thus exact numbers are not comparable.

> It supports solid compression[1] which
> compresses multiple files into one block like tar.xz, but unlike tar.xz
> can use more than one block: "Later versions of 7-zip use a variable
> solid block size, so that only a limited amount of data must be
> processed in order to extract one file".

Yeah but the default block size is 2GB, which would make every single .deb
in the archive effectively fully solid.  You can fine-tune the values, but
example numbers don't appear like they'd help much.

And just tested, -ms=on vs -ms=16m:
-rw-r--r--  1 kilobyte kilobyte 1087957645 May 13 14:37 u.7z
-rw-r--r--  1 kilobyte kilobyte 1253369019 May 13 14:50 u16m.7z

So the space loss is massive.


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