Re: Fix a server crash problem from pg_get_database_ddl

> On Apr 26, 2026, at 22:50, Andrew Dunstan <andrew@dunslane.net> wrote:
> 
> 
> 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
> 

The v1 patch raises an error when the tablespace name is NULL.

PFA v2: removed hint from the error message, because I now consider the hint might not be necessary.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/