Re: [HACKERS] shared memory based stat collector (was: Sharing record typmods between backends)

Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Aug 14, 2017 at 12:16 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Just FYI, the only values being reported by buildfarm animals are
>> "posix", "sysv", and "windows".  So while mmap may be a thing,
>> it's an untested thing.

> I'm pretty sure I dev-tested it before committing anything, but,
> certainly, having ongoing BF coverage woudn't be a bad thing.

Looking closer, the reason those are the only reported values is
that those are the only possible results from initdb's
choose_dsm_implementation().  So the real question here is whether
"mmap" should be considered to dominate "sysv" if it's available.
If so, why isn't choose_dsm_implementation() trying it; and if not,
why are we carrying it?
        regards, tom lane