Re: two shared memory segments?

"Ed L." <pgsql@bluepolka.net> writes:
> I have a cluster configured for ~800MB of shared memory cache
> (shared_buffers = 100000), but ipcs shows TWO shared memory
> segments of ~800MB belonging to that postmaster.  What kind of
> a problem do I have here?

I'd say that you had a backend crash, causing the postmaster to abandon
the original shared memory segment and make a new one, but the old
segment is still attached to by a couple of processes.

There was a bug awhile back whereby the stats support processes failed
to detach from shared memory and thus would cause a dead shmem segment
to hang around like this.  What PG version are you running?

            regards, tom lane