Re: Add --system-identifier / -s option to pg_resetwal

On Sat, May 31, 2025 at 2:52 PM Nikolay Samokhvalov <nik(at)postgres(dot)ai> wrote:

> I was just involved in a DR case, where we needed to change system ID in
> control data, and noticed that there is no such capability, officially – so
> I thought, it would be good to have it
>
> the attached patch adds a new -s / --system-identifier option to
> pg_resetwal that allows users to change the database cluster's system
> identifier; it can be useful when you need to make a restored cluster
> distinct from the original, or when cloning for testing
>
> some aspects about the patch:
> - accepts positive 64-bit integers only (zero not allowed)
> - requires interactive confirmation or --force flag for safety
> - detects non-TTY environments and requires --force in scripts
> - included input validation and error handling
> - updated docs with clear warnings about compatibility
> - added tests, including some edge cases
>
> looking forward to hearing feedback!
>
+1

Like the idea. I did a manual code review. It's a small patch, very
focused, and includes the proper docs.
It's very well thought out (I Iike the --force requirement for scripts).

The only thing I saw was that the code basically accepts Y or y, and all
else is considered "N". for that reason,
I suggest that this line:
printf(_("Continue? (y/n) "));

Would be more clear as:
printf(_("Continue? (y/n) [n]"));

indicating the N is the default answer. if you put anything other than Y
or y... N will be picked.

But this is almost trivial, but I wanted to be thorough.

Regards!