Re: Allow workers to override datallowconn

On Thu, Feb 22, 2018 at 8:17 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:

> Hi,
>
> On 2018-02-22 19:01:35 +0100, Magnus Hagander wrote:
> > In working on the checksumhelper patch, we came across wanting a
> background
> > worker to be allowed to bypass datallowconn for a database. Right now we
> > didn't take care of that, and just said "you have to ALTER TABLE" first.
>
> I suspect you mean ALTER DATABASE, rather than table? ;)
>

Um. Yes :)

> I wonder if we don't want this to be a slightly more generic
> facility. E.g. pg_upgrade has the same need. Perhaps we whould
> superuser-only connection-establishment only option that allows
> connecting to a database even if datallowconn = false, and then
> additionally allow to pass connection arguments to
> BackgroundWorkerInitializeConnection()? It seems fairly reasonable to
> want to establish different GUCs via normal GUC-y mechanisms when
> establishing a bgworker connection...
>

In a background worker you can just set the parameter using
SetConfigOption(), no? That seems a lot easier than turning things in to a
kv pair and back...

I can see the point for having such a parameter for pg_upgrade, but I'm not
sure we'd necessarily want to overload them.

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>