Re: Libpq support to connect to standby server as priority

From: Dave Cramer [mailto:pg@fastcrypt.com]
>       The original desire should have been the ability to connect to a
> primary or a standby.  So, I think we should go back to the original thinking
> (and not complicate the feature), and create a read only GUC_REPORT variable,
> say, server_role, that identifies whether the server is a primary or a
> standby.
>
>
>
> 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.