Re: pg_upgrade fails with an error "object doesn't exist"

Daniel Gustafsson <daniel(at)yesql(dot)se> writes:
> On 16 Jun 2025, at 09:29, Vaibhav Dalvi <vaibhav(dot)dalvi(at)enterprisedb(dot)com> wrote:
>> Why can't we strictly restrict object creation in pg_catalog?

> Do you have allow_system_table_mods set to ON by any chance? As Laurenz said,
> such creation is already restricted, but it can be circumvented by using said
> GUC (which is *not* intended for production usage).

I think that setting only applies to creating or modifying *tables*,
not functions. The point of it is to keep you from breaking the C
code's assumptions about the layout of system catalogs.

Having said that, I don't see a problem here. You're not going
to be able to create/modify functions in pg_catalog unless you
are superuser (or a superuser gave you permissions you shouldn't
have). There are already a near-infinite number of ways
for a superuser to break the system, so this one isn't making it
detectably worse. Furthermore, there are legitimate use-cases
for adding/changing functions there. (I recall that the old
"adminpack" extension used to do so, for example, and there are
probably others that still do.)

regards, tom lane