>> 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