Horton

RE: [PROPOSAL] Termination of Background Workers for ALTER/DROP DATABASE

Aya Iwata (Fujitsu) <iwata.aya@fujitsu.com>

View thread
From: "Aya Iwata (Fujitsu)" <iwata.aya@fujitsu.com>
To: 'Pavel Stehule' <pavel.stehule@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Peter Smith <smithpb2250@gmail.com>, Chao Li <li.evan.chao@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-12-17T13:31:51Z
Lists: pgsql-hackers 
Hi Pavel-san,

>> So maybe there should be ALTER DATABASE ... RENAME ... FORCE - or if FORCE can terminare all workers (without special FLAG) ?
> 
> For the proposed feature, we've added a flag allowing each extension developer to decide whether to terminate it via DROP/ALTER DATABASE.
> Adding a FORCE option to ALTER to let database definition modifiers decide whether to force termination of background workers might be better discussed in a separate thread.
> 
> When I thought about it - there can be a second alternative.
> 
> Introduce a pair of flags BGWORKER_INTERRUPTABLE and BGWORKER_PROTECTED (the names can be enhanced or changed). BGWORKER_INTERRUPTABLE can be default. 
> ALTER DATABASE RENAME and related commands can stop any non protected workers. ALTER DATABASE RENAME FORCE can stop any workers (including protected). 

I can't image any use cases for BGWORKER_PROTECTED. Do you have any idea?
Also, I think the parameter settings might get a complicated.
If we start discussing the "FORCE" option, it is better to think about this parameter.

> Is there any reason why BGWORKER_INTERRUPTABLE cannot be default? Probably nobody would block some possibly common operations on database level without strong reason.

As Michael-san mentioned in a previous email, this behavior has remained unchanged since bgworkers were introduced in v9.3. 
I don't see a compelling reason to alter it now.  Additionally, this specification can be modified later.

Best Regards,
Aya Iwata