psql-mail@freeuk.com writes:
> The server has 4GB of memory and is not running any other services - so
> i wouldn't expect there to be memory shortage problems.
That has nothing whatever to do with how much memory the kernel will let
any one process have. Check what ulimit settings the postmaster is
running under (particularly -d, -m, -v).
> I have since changed the kernel settings to allow 1GB of shared mem and
> changed shared_buffers in postgresql.conf to request just under that.
If anything, that's counterproductive for this problem. I'm not sure
whether shared memory is counted against your ulimit -d, but it might
be.
regards, tom lane