Re: pg_checksums?

Hi Bruce, hi Daniel,

> On Oct 27, 2023, at 23:21, Bruce Momjian <bruce@momjian.us> wrote:
>
> On Fri, Oct 27, 2023 at 10:45:16PM +0200, Daniel Gustafsson wrote:
>>> On 27 Oct 2023, at 20:34, Paul Förster <paul.foerster@gmail.com> wrote:
>>
>>> a) why isn't it possible to enable checksumming while a database cluster is up?
>>
>> It is surprisingly complicated to enable checksums on a live cluster, a patch
>> was submitted a while back but ultimately never made it into postgres.  The
>> below threads may shine some light on the problem:
>>
>> https://www.postgresql.org/message-id/flat/CABUevEx8KWhZE_XkZQpzEkZypZmBp3GbM9W90JLp%3D-7OJWBbcg%40mail.gmail.com
>>
https://www.postgresql.org/message-id/flat/560A2239-5DE2-4B9C-92BC-878C6822F47C%40yesql.se#10b665b2193445a3d7f24be7917a952c
>
> Yeah, it was a big surprise that this feature was so hard to implement
> because we have _no_ infrastructure for having multiple data layouts
> active in a live system.  The discussion eventually made that clear.
>
> If we have more features that need this kind of dynamic ability, we
> might revisit this feature too.

Ok, I see.

But unfortunately still, my questions c) and d) are unanswered. I'd especially be interested in an answer to c), i.e.
isit *safe* to "pg_checksum -e" the replica instance in a patroni cluster, switch over, and then do the other one? 

Cheers
Paul