Re: Offline enabling/disabling of data checksums

On Fri, Mar 15, 2019 at 09:52:11AM +0100, Magnus Hagander wrote:
> As I said, that's a big hammer. I'm all for having a better solution. But I
> don't think it's acceptable not to have *any* defense against it, given how
> bad corruption it can lead to.

Hm... It looks that my arguments are not convincing enough. I am not
really convinced that there is any need to make that the default, nor
does it make much sense to embed that stuff directly into pg_checksums
because that's actually just doing an extra step which is equivalent
to calling pg_resetwal, and we know that this tool has the awesome
reputation to cause more harm than anything else. At least I would
like to have an option which allows to support the behavior to *not*
update the system identifier so as the cases I mentioned would be
supported, because then it becomes possible to enable checksums on a
primary with only a failover as long as page copies are not directly
involved and that all operations go through WAL. And that would be
quite nice.
--
Michael