>> I'm confused as to how this would work. Who or what determines if the server
>> is a primary or standby?
>
> Overall, the server determines the server role (primary or standby) using the
> same mechanism as pg_is_in_recovery(), and set the server_role GUC parameter.
> As the parameter is GUC_REPORT, the change is reported to the clients using
> the ParameterStatus ('S') message. The clients also get the value at
> connection.
But pg_is_in_recovery() returns true even for a promoting standby. So
you have to wait and retry to send pg_is_in_recovery() until it
finishes the promotion to find out it is now a primary. I am not sure
if backend out to be responsible for this process. If not, libpq would
need to handle it but I doubt it would be possible.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
