Re: [HACKERS] [COMMITTERS] pgsql: Add psql variables showing server version and psql version.

Simon Riggs <simon@2ndquadrant.com> writes:
> Does raise the further question of how psql behaves when we connect to
> a pre-10 server, so we have SERVER_VERSION_NUM but yet it is not set.

Huh?  The variable will be set in any case.  It should be correct for any
server version we might find in the wild --- so far as I can tell from the
commit history, every version supporting FE/BE protocol version 3 has sent
server_version at connection start.  With a pre-7.4 server, it looks like
the variables would be set to "0.0.0" and "0" respectively.
        regards, tom lane