Re: pg_control_checkpoint(): add "data_checksum_version" (Pg19)?

> On 10 Aug 2026, at 16:21, Ian Lawrence Barwick <barwick(at)gmail(dot)com> wrote:
> 2026年8月10日(月) 22:30 Fujii Masao <masao(dot)fujii(at)gmail(dot)com>:

>> On Mon, Aug 10, 2026 at 9:39 PM Ian Lawrence Barwick <barwick(at)gmail(dot)com> wrote:
>>> The function "get_checksum_state_string()" which performs the conversion is in
>>> src/backend/access/rmgrdesc/xlogdesc.c, which AFAIR can't be linked from
>>> frontend utilities, so we'd either have to move that somewhere else (maybe
>>> src/common/controldata_utils.c?) or duplicate it.

I originally opted against displaying the mapped name to keep
pg_control_checkpoint a way to extract the raw data, but thinking about it
might be more useful to show the mapped value since the mapping is private.

>> Agreed. I think moving it to common is better than duplicating the mapping.
>>
>> src/common/controldata_utils.c seems like a reasonable place, since
>> this state is stored in the control/checkpoint data and both pg_controldata
>> and pg_control_checkpoint() already use controldata_utils.
>
> TBH it feels a little odd there because it's not really specific to
> the controldata output functions, but it has to go somewhere, I guess.

Yeah, I'm not convinced it's the right place but that being said I also don't
have a better idea yet. If I can't think of a better place by the time the
tree is open I say we go with this placement.

Thanks for the updated patch!

--
Daniel Gustafsson