Re: Fix a server crash problem from pg_get_database_ddl

On 2026-04-23 Th 2:47 AM, SATYANARAYANA NARLAPURAM wrote:
>
>
>
> Thanks for printing out that. Yes, they are similar.
>
> I agree with what Tom said in [2]:
> ```
> This is not a bug. This is a superuser intentionally breaking
> the system by corrupting the catalogs. There are any number
> of ways to cause trouble with ill-advised manual updates to a
> catalog table. Try, eg, "DELETE FROM pg_proc" (... but not in
> a database you care about).
> ```
>
> So, let me take back this patch.
>
> [2]
> https://www.postgresql.org/message-id/1538113.1768921841@sss.pgh.pa.us
>
>
> In this case, it is a very corner case but not something superuser
> intentionally breaks.
> For example, a concurrent tablespace drop + database ddl to assign a
> different tablespace or default.
> We aren't acquiring Access Share lock on the DB in this function
> (intentional) so it is a good practice
> to do the null checks. Of course, it makes more sense to add this
> comment while doing a code review.
> I will let Tom and others chime in with their thoughts on fixing this.
>
> Attached an injection point test to show the race. Not intended to commit.
>
>

I agree if there's a race condition we should protect against it. I
don't much like the idea of silently ignoring it, though. Raising an
error seems more like the right thing to do.

cheers

andrew

--
Andrew Dunstan
EDB:https://www.enterprisedb.com