Re: let's make the list of reportable GUCs configurable (was Re: Add %r substitution for psql prompts to show recovery status)

On Sat, 12 Oct 2019 at 05:05, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2019-10-11 16:30:17 -0400, Robert Haas wrote:
> >> But, if it does need to be changed, it seems like a terrible idea to
> >> allow it to be done via SQL. Otherwise, the user can break the driver
> >> by using SQL to set the list to something that the driver's not
> >> expecting, and there's nothing the driver can do to prevent it.
>
> > Uhm. The driver can just ignore GUCs it's not interested in, like our
> > docs have told them for a long time?
>
> Certainly it should do that; but the problematic case is where it
> *doesn't* get told about something it's depending on knowing about.
>
> regards, tom lane
>

Here's an updated patch that addresses some of Andres' concerns
specifically does not use strtok.

As far as addressing connection poolers goes; one thought is to use the
cancellation key to "validate" the SQL.
This should be known to all drivers and pool implementations. Thoughts ?

Dave