Re: WIP: WAL prefetch (another approach)

Simon Riggs  writes:

> On Thu, 7 Apr 2022 at 08:46, Thomas Munro  wrote:
>
>> With that... I've finally pushed the 0002 patch and will be watching
>> the build farm.
>
> This is a nice feature if it is safe to turn off full_page_writes.
>
> When is it safe to do that? On which platform?
>
> I am not aware of any released software that allows full_page_writes
> to be safely disabled. Perhaps something has been released recently
> that allows this? I think we have substantial documentation about
> safety of other settings, so we should carefully document things here
> also.

Our WAL reliability docs claim that ZFS is safe against torn pages:

https://www.postgresql.org/docs/current/wal-reliability.html:

    If you have file-system software that prevents partial page writes
    (e.g., ZFS), you can turn off this page imaging by turning off the
    full_page_writes parameter.

- ilmari