Re: Return value of pg_promote()

Fujii Masao <masao.fujii@oss.nttdata.com>

From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Laurenz Albe <laurenz.albe@cybertec.at>, Ashutosh Sharma <ashu.coek88@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-06-07T16:25:38Z
Lists: pgsql-hackers

On 2023/06/07 2:00, Laurenz Albe wrote:
> On Tue, 2023-06-06 at 16:35 +0530, Ashutosh Sharma wrote:
>> At present, pg_promote() returns true to the caller on successful
>> promotion of standby, however it returns false in multiple scenarios
>> which includes:
>>
>> 1) The SIGUSR1 signal could not be sent to the postmaster process.
>> 2) The postmaster died during standby promotion.
>> 3) Standby couldn't be promoted within the specified wait time.
>>
>> For an application calling this function, if pg_promote returns false,
>> it is hard to interpret the reason behind it. So I think we should
>> *only* allow pg_promote to return false when the server could not be
>> promoted in the given wait time and in other scenarios it should just
>> throw an error (FATAL, ERROR ... depending on the type of failure that
>> occurred). Please let me know your thoughts on this change. thanks.!
> 
> As the original author, I'd say that that sounds reasonable, particularly
> in case #1.  If the postmaster dies, we are going to die too, so it
> probably doesn't matter much.  But I think an error is certainly also
> correct in that case.

+1

Regards,

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



Commits

  1. Tweak pg_promote() to report failures on kill() or postmaster failures