Greetings,
Is there a strong reason to disallow reloading server key and cert files during the PostgreSQL reload?
Basically, once you run multiple databases in a cluster and use different DNS names to connect to different databases (in order for those databases to be moved somewhere without changing the client code), and enable SSL certificate checking, the problem becomes evident: in order to add a new database to the existing cluster you have to add its name to the SSL certificate for the server, and in order for this changes to come into effect you have to restart the server.
In the documentation for server cert and key file there is a notice that this parameter can only be reloaded during the server start. It seems that the only place the backend certificates are loaded is inside the secure_initialize, which, in order, calls initialize_SSL().
From my point of view, I see nothing preventing separation of the certificate reload code and SSL library initialization and calling the former during the server reload. It might happen that with the new certificate file that some of the existing connections will be unable to reconnect, or, if the certificate is invalid, the server will be unable to restart, but this are the sort of problems that also happen with reload of pg_hba.conf as well, so these alone does not sound like a significant showstopper.
