Gavin Sherry <swm@linuxworld.com.au> writes:
> I was trying to be paranoid about users who have multiple postmasters on
> the same machine and want to share a table space while both systems are
> live. There'd be no mechanism to test for that situation if we didn't have
> something like a postmaster.pid file. Is this being a little too paranoid?
Hm. AFAICS there is no safe situation in which a tablespace directory
could be shared by two different installations (== toplevel $PGDATA
directories). I don't think we need a dynamic postmaster.pid-type lock
to protect them. What might make sense is some sort of marker file in a
tablespace directory that links back to the owning $PGDATA directory.
CREATE TABLESPACE should create this, or reject if it already exists.
regards, tom lane
