The executables that you (might) care about are:

  dbscripts/
  ├── cron-jobs/
  │   ├── db-cleanup                  [Parabola only]
  │   ├── devlist-mailer
  │   ├── ftpdir-cleanup
  │   ├── integrity-check
  │   ├── make_repo_torrents          [Parabola only]
  │   ├── sourceballs
  │   ├── update-web-db               [Arch Linux only]
  │   └── update-web-files-db         [Arch Linux only]
  ├── db-check-nonfree                [Parabola only]
  ├── db-check-nonfree-in-db          [Parabola only]
  ├── db-check-package-libraries      [Parabola only]
  ├── db-check-repo-sanity            [Parabola only]
  ├── db-check-unsigned-packages      [Parabola only]
  ├── db-check-unsigned-packages.py   [Parabola only]
  ├── db-import-archlinux-any-to-ours [Parabola only]
  ├── db-import-archlinux-pkg         [Parabola only]
  ├── db-import-archlinux-src         [Parabola only]
  ├── db-import-archlinuxarm-pkg      [Parabola only]
  ├── db-init                         [Parabola only]
  ├── db-move
  ├── db-remove
  ├── db-repo-add
  ├── db-repo-remove
  ├── db-update
  ├── make_individual_torrent         [Parabola only]
  └── testing2x                       [Arch Linux only]

Ok, now let's talk about what those are.

There are 3 "main" programs:

 - db-update : add packages to repositories
 - db-move   : move packages from one repository to another
 - db-remove : remove packages from repositories

Of course, sometimes things go wrong, and you need to drop to a
lower-level, but you don't want to go all the way down to pacman's
repo-add/repo-remove.  So, we have:

 - db-repo-add
 - db-repo-remove

Now, we'd like to be able to check that the repos are all OK, so we
have

 - cron-jobs/integrity-check

Instead of enhancing integrity-check, Parabola developers have decided
to write multiple stand-alone tools that should probably be merged
into integrity-check

 - db-check-*

When we remove a package from a repository, it stays in the package
"pool".  We would like to be able to eventually remove packages from
the pool, to reclaim the disk space:

 - cron-jobs/ftpdir-cleanup
 - cron-jobs/db-cleanup

Both of these programs do the exact same thing.  Parabola developers
decided to write their own from scratch, instead of modifying
ftpdir-cleanup.  They should eventually be merged.

But, Parabola doesn't just publish our own packages, we also import
packages from elsewhere:

 - db-import-${source}*

Unfortunately, these scripts are horribly duct-taped together and are
aweful.  I hate them.

Things that haven't been mentioned yet:

 - cron-jobs/devlist-mailer
 - cron-jobs/make_repo_torrents
 - cron-jobs/sourceballs
 - db-init
 - make_individual_torrent