WIP: raise error when submitting invalid ALTER SYSTEM command

Hi all,

ALTER SYSTEM currently does not raise error upon invalid entry. Take for example:

alter system set superuser_reserved_connections = 10;
> ALTER SYSTEM
alter system set max_connections = 5;
> ALTER SYSTEM

The database will now fail to restart without manual intervention by way of editing the autoconf file (which says "# Do
notedit this file manually!" on its first line).
 

The attached WIP patch is intended to raise an error on invalid ALTER SYSTEM commands before being written out to the
filesystem.Hopefully this behavior is more intuitive.
 

Thanks
--
Jordan Deitch
https://id.rsa.pub/