protocol_version (PGconn)

    /*
     * call-seq:
     *  conn.protocol_version -> Integer
     *
     * The 3.0 protocol will normally be used when communicating with PostgreSQL 7.4
     * or later servers; pre-7.4 servers support only protocol 2.0. (Protocol 1.0 is
     * obsolete and not supported by libpq.)
     */
    static VALUE
    pgconn_protocol_version(VALUE self)
    {
            return INT2NUM(PQprotocolVersion(get_pgconn(self)));
    }