Re: WIP: WAL prefetch (another approach)

On Tue, 12 Apr 2022 at 16:41, Tomas Vondra
<tomas.vondra@enterprisedb.com> wrote:
>
> On 4/12/22 15:58, Simon Riggs wrote:
> > On Thu, 7 Apr 2022 at 08:46, Thomas Munro <thomas.munro@gmail.com> 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.
> >
>
> I don't see why/how would an async prefetch make FPW unnecessary. Did
> anyone claim that be the case?

Other way around. FPWs make prefetch unnecessary.
Therefore you would only want prefetch with FPW=off, AFAIK.

Or put this another way: when is it safe and sensible to use
recovery_prefetch != off?

-- 
Simon Riggs                http://www.EnterpriseDB.com/