I’m doing a tidy-up of our RT 3.6 database prior to an upgrade to 3.8,
and part of that is clearing out all the old dead users. I have a
regular job that uses RTx-Shredder to clean out deleted tickets, but
until recently I hadn’t thought about users. As a result, I had about
200000 users in a system where I know there are only about 1000 real
users, absolute max. The rest will all be one-off addresses from spams
which have since been deleted.

I’ve been using:
./rtx-shredder --force --plugin
to shred users which are no longer associated with any tickets.

After a couple of weeks, I’m down to 50000 users, but I’ve hit this error:
ERROR: Dependecies list have reached its limit.
See $RT::DependenciesLimit in RTx::Shredder docs.

I’ve increased RT::DependenciesLimit to 4000 (in a few steps), and I
still hit this error. I’m getting wary of increasing it too much more
without knowing what is actually going on in the database. Is there any
way to find out which user is causing this problem? We have had a few
mail loops in the past which might have caused this many tickets to
have been associated with one user who is now dead, but I’d like to be sure!

So is there a SQL query that will give this information? I guess it’s
somewhere is CachedGroupMembers or Principals, but I don’t understand
how it all fits together.

Thanks in advance for any pointers…