Re: Initdb-time block size specification

On Sat, Jul  1, 2023 at 12:21:03AM +0200, Tomas Vondra wrote:
> On 6/30/23 23:53, Bruce Momjian wrote:
> > For a 4kB write, to say it is not partially written would be to require
> > the operating system to guarantee that the 4kB write is not split into
> > smaller writes which might each be atomic because smaller atomic writes
> > would not help us.
> 
> Right, that's the dance we do to protect against torn pages. But Andres
> suggested that if you have modern storage and configure it correctly,
> writing with 4kB pages would be atomic. So we wouldn't need to do this
> FPI stuff, eliminating pretty significant source of write amplification.

I agree the hardware is atomic for 4k writes, but do we know the OS
always issues 4k writes?

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Only you can decide what is important to you.