[Yum] metadata compression

James Antill james-yum at and.org
Mon Apr 20 21:23:25 UTC 2009

Joshua Bahnsen <archrival at gmail.com> writes:

> I don't know the roadmap for yum, so I didn't realize that sqlite files was
> the way to go. It does make sense, though.
> I won't go into details about the RHEL 3 and RHEL 4 yum setup I have...
> I have posted 3 compressed versions of other.xml from rhel-i386-server-5
> here:
> http://thejoshwa.com/upload/other.xml.7z
> http://thejoshwa.com/upload/other.xml.bz2
> http://thejoshwa.com/upload/other.xml.gz
> All were compressed using the maximum compression available for each (gzip
> --best, bzip2 --best, 7z a -t7z -mx=9 -m0=lzma).
> You can see the difference for yourself.

 Interesting, "7z" appears to be much faster than lzip ... and
joyfully incompatible with either lzip or lzma (at least in your above
use case), but the file sizes are close enough. After converting to
.sqlite I get:

 121M other.xml.sqlite
 5.0M other.xml.sqlite.7z
  27M other.xml.sqlite.bz2
  39M other.xml.sqlite.gz
 5.5M other.xml.sqlite.lz
 5.4M other.xml.sqlite.lzma

...which is interesting, but looking at the data (Eg. primary,
filelists, etc.) it looks like lzip/lzma/7z/etc. are just seeing
that for each version of each package most of the changelog is
identical. This means that's it's only a big win for changelog data,
and maybe only enough of one while we continue to put every changelog
entry since the beginning of time into the metadata.

James Antill -- james at and.org

More information about the Yum mailing list