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At the start of dnf upgrade, dnf shows MBs of download for some repos. e.g. For Visual Studio Code in below it downloaded ~10MB

$ sudo dnf upgrade
Fedora 33 - x86_64 - Updates                    7.8 kB/s |  15 kB     00:01    
Fedora 33 - x86_64 - Updates                    166 kB/s | 2.3 MB     00:13    
RPM Fusion for Fedora 33 - Free - Updates       2.0 kB/s | 2.8 kB     00:01    
skype (stable)                                  2.1 kB/s | 2.9 kB     00:01    
Visual Studio Code                              2.8 kB/s | 3.0 kB     00:01    
Visual Studio Code                               90 kB/s |  10 MB     01:59    

This is before y/N prompt i.e. actual update packages have not started downloaded yet.

Just curious, what does this download contain?

3 Answers 3

4

That's the metadata of the repositories that's used to know everything related to the packages you can access. It's usually a file called repodata.xml, that can be compressed, where there are tons of info about the packages that are available, including version of those packages and groups of packages available.

With this info, DNF/YUM are able to know if you have an update available or if a package that you're trying to install exists or don't, and which dependencies are needed to install each package.

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DNF is downloading a list of available packages to determine if updates and/or new packages are available.

0

If you're coming from the world of APT/DEB, then you needed to run apt update manually, so that apt upgrade/apt install made any sense.

Yum/DNF does that automatically based on the timestamps of the last package database update.

This download operation normally occurs every several hours (I can't say exactly), so if you run dnf several times in a row in a relatively short period of time, it won't download the packages database again and again.

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