[anarazel]

> I'd be curious how much effort and specific shared-memory-IPC-expertise is required on the part of the Postgres maintainers to keep the shared memory layer capable and secure.

I don't think security plays a huge role for shared memory in postgres - if an attacker gains arbitrary code execution in one postgres backend, the installation is hosed. No need to go through SHM to escalate to other backends, there's easier ways.

WRT capable: There's definitely substantial costs due to using inter-process shared memory. But it's more an architectural cost, rather than something that everyone has to bear while just doing mostly unrelated hacking. Some features get harder, less flexible and require more code.

FWIW, there's some work towards moving towards a threaded connection model. Still some way to go, but I expect it to happen eventually.