On Fri, 29 Dec 2023 at 19:38, Tom Lane <t...@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.
