On Fri, 29 Dec 2023 at 19:38, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > 2. It paves the way for GUCs that can only be set using a protocol
> > message (and not using SET).
>
> This is assuming facts not in evidence.
How about instead of talking about protocol-only GUCs (which are
indeed currently a theoretical concept), we start considering this
patch as a way to modify parameters for protocol extensions. Protocol
extension parameters (starting with _pq_.) can currently only be
configured using the StartupMessage and afterwards there is no way to
modify them.
I believe [1], [2] and [3] from my initial email could all use such
protocol extension parameters, if those parameters could be changed
after the initial startup.