Re: Change log level for notifying hot standby is waiting non-overflowed snapshot

On 2025/03/24 23:18, torikoshia wrote:
> On 2025-03-24 00:08, Fujii Masao wrote:
>
>>>
>>> Do you also think the errhint message is unnecessary?
>>> I agree with your idea to add a description of the overflowed subtransaction in the manual, but I'm not sure all users will be able to find it.
>>> Some people may not understand what needs to be done to make the snapshot ready for hot standby.
>>> I think adding an errhint may help those users.
>>
>> I see your concern that users might overlook the documentation and
>> struggle to find a solution. However, I still believe it's better to
>> include this information in the documentation rather than logging it
>> as a hint. Since the scenario where the hint would be useful is
>> relatively rare, logging it every time might be more confusing than helpful.
>
> Thanks for your opinion and it sounds reasonable.
>
> Attached an updated patch.

Thanks for updating the patch!

In high-availability.sgml, the "Administrator's Overview" section already
describes the conditions for accepting hot standby connections.
This section should also be updated accordingly.

+ brought the system to a consistent state. However, overflowed
+ subtransactions may also delay snapshot readiness for hot standby. In such
+ case, the issue can be resolved by closing the transaction containing the
+ overflowed subtransactions. All connections accepted by the hot standby
+ are strictly read-only; not even temporary tables may be written.

It would be better to move this explanation about overflowed subtransactions
to the "Administrator's Overview" section.

- case CAC_NOTCONSISTENT:
+ case CAC_NOTCONSISTENT_OR_OVERFLOWED:

This new name seems a bit too long. I'm OK to leave the name as it is.
Or, something like CAC_NOTHOTSTANDBY seems simpler and better to me.
Thought?

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION