Re: Names of run-time configuration parameters (was: Limiting the operations that client-side code can perform upon its database backend's artifacts)

Hi,

On Sat, Oct 01, 2022 at 02:05:53PM +0200, Peter J. Holzer wrote:
> On 2022-09-30 17:59:01 -0700, Bryn Llewellyn wrote:
> > set rls.tenant_id=42;
>
> This works because there is a "." in the name. Without the "."
> PostgreSQL complains:
>
> hjp=> set rls_tenant_id=42;
> ERROR: unrecognized configuration parameter "rls_tenant_id"
>
> I think I sort of knew this but had forgotten about it, so checked the
> manual for the exact rules. Unfortunately I couldn't find them (I
> checked https://www.postgresql.org/docs/14/sql-set.html,
> https://www.postgresql.org/docs/14/config-setting.html,
> https://www.postgresql.org/docs/14/functions-admin.html#FUNCTIONS-ADMIN-SET,
> and browser the table of content and the index).
>
> From the documentation I get the impression that you can only set
> existing parameters, not your own.
>
> I therefore suggest adding something like this to the section
> "configuration_parameter" in
> https://www.postgresql.org/docs/14/sql-set.html:
>
> | In addition, any name including a single dot (".") can be set. This
> | allows an application to define its own run-time parameters. Using the
> | application name as a prefix reduces the probability of name conflicts
> | with other applications or extensions.
>
> (This of course assumes that the behaviour is intentional and not a
> bug.)

This is intentional, and documented at
https://www.postgresql.org/docs/14/runtime-config-custom.html.