Fedora 29 To Change DNF's Repository Metadata Compression To Zchunk

Fedora 29 continues looking like a rather ambitious release with a growing number of changes, including at some of the lowest levels of the system. The latest feature proposal is on changing the compression scheme used by the DNF package manager's repository metadata.

Right now Fedora's DNF uses XZ and Gzip formats for the compressing of the repository metadata. With Fedora 29+, Zchunk would instead be used.

Using Zchunk should provide for better compression and only needing to download the differences between any earlier copies of the metadata on the system. With this change, users should see a "significant reduction" in the download size when acquiring the repository metadata for new package installation or updates.

Fedora would still keep XZ and Gzip metadata around for those wanting to upgrade from older Fedora releases where their DNF is not Zchunk-aware while any new installations or those post-upgrade would default to using the new Zchunk scheme.

More details via this change proposal.

For those that don't recall, back in May is when Zchunk was announced with its format inspired by Zsync and Casync while being designed for delta-friendly files. Zchunk relies upon Zstd for compression.