[arch-general] Is it possible to update 3rd party repo index without updating all?

[David C. Rankin]

All,

  I would like to update a 3rd party repo index WITHOUT updating any other
index. Like adding a --repo option to 'Pacman -Sy'. e.g.

  Pacman -Sy -r somerepo

  This would be handy when you want to update a 3rd party index and install
updated packages WITHOUT updating core, community, extra... to avoid having to
do a full system update just to get new packages from a non-arch repo. There are
times when I just want to install a new external package or set of packages but
not do a full update involving the kernel, etc.

  I've looked at all the pacman options and there does not seem to be a way to
do this. (Yes - I do understand why all Arch repos must be updated together in
order to avoid the partial-update issues) But, with a 3rd party repo, that isn't
a concern.

  Is there a way to do this via pacman, and if not, is there a way to manually
download the new 3rd party index and add it to the cache to accomplish the same
thing? Like just replacing the current .db index in /var/lib/cache/pacman/sync
with the new one?[1]

  What say the experts?

Footnotes:
[1]  I am asking before trying to avoid screwing something up, so no, I haven't
tried it yet.

-- 
David C. Rankin, J.D.,P.E.