Ivan Voras <ivoras(at)freebsd(dot)org> writes:
> Ideally, the C module would create its own "custom variable class,"
> named e.g. "module", then define some setting, e.g. "module.setting".
> The users would then execute an SQL command such as "SET SESSION
> module.setting='something'", and the module would need to pick this up
> in the C function.
Plenty of examples of that in contrib/ ...
regards, tom lane