Re: Reject invalid databases in pg_get_database_ddl()

On Fri, Apr 17, 2026 at 10:16 AM Amit Langote <amitlangote09(at)gmail(dot)com>
wrote:

> On Fri, Apr 17, 2026 at 10:47 AM Euler Taveira <euler(at)eulerto(dot)com> wrote:
> > On Thu, Apr 16, 2026, at 8:46 PM, Amit Langote wrote:
> > >
> > > Thanks. Will push the attached shortly.
> >
> > I think the errhint() is excessive in this context. It makes sense if
> you are
> > executing ALTER DATABASE, for example.
>
> Yeah, agreed.
>
> > I suggest a message like
> >
> > database \"%s\" is an invalid database
>
> Or just drop it, because the errmsg already says "invalid database %s".
>
> > Regarding the test case suggested by Japin Li, I don't think it is worth
> because
> > it is a transient state (unless something bad happened and pg_database
> contains
> > a dangling row.)
>
> Agreed.
>

+1. As this is an edge case failure, it’s not worth extending test time.

>
> Patch updated.
>
> --
> Thanks, Amit Langote
>

+ /*
+ * Reject invalid databases: datconnlimit = -2 would be emitted as
+ * CONNECTION LIMIT = -2, which cannot be executed.
+ */

This comment looks a bit too centered on datconnlimit=-2, but the real
issue is that an invalid pg_database row should not be deparsed into DDL.
So, maybe rephrase like:

/*
* Reject invalid databases. Deparsing a pg_database row in invalid state
* can produce SQL that is not executable, such as CONNECTION LIMIT = -2.
*/

Regards,
Xunqi Hu