Re: Offline enabling/disabling of data checksums

On Thu, Mar 14, 2019 at 1:23 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Wed, Mar 13, 2019 at 12:24:21PM +0100, Magnus Hagander wrote:
> > Enabling or disabling the checksums offline on the master quite clearly
> > requires a rebuild of the standby, there is no other way (this is one of
> > the reasons for the online enabling in that patch, so I still hope we can
> > get that done -- but not for this version).
>
> I am curious to understand why this would require a rebuild of the
> standby. Technically FPWs don't update the checksum of a page when it
> is WAL-logged, so even if a primary and a standby don't agree on the
> checksum configuration, it is the timing where pages are flushed in
> the local instance which counts for checksum correctness.
>

Are you suggesting we should support running with a master with checksums
on and a standby with checksums off in the same cluster? That seems.. Very
fragile.

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>