> Also, there was a time when you couldn't do vacuum full on system
> tables do to locking issues, and had to take the db down to single
> user mode to do so.
There was a short period when *concurrent* vacuum fulls on just the
wrong combinations of system catalogs could deadlock (because they both
needed to look up stuff in the other one). AFAIK we fixed that. It's
never been the case that it didn't work at all.
regards, tom lane