Re: Vacuum full connection exhaustion

On Fri, Aug 9, 2024 at 1:02 AM David Rowley <dgrowleyml@gmail.com> wrote:

> On Fri, 9 Aug 2024 at 02:12, Christophe Pettus <xof@thebuild.com> wrote:
> > VACUUM FULL takes an exclusive lock on the table that it is operating
> on.  It's possible that a connection becomes blocked on that exclusive lock
> waiting for the VACUUM FULL to finish, the application sees the connection
> stopped and fires up another one (this is common in container-based
> applications), that one blocks... until all of the connections are full of
> queries waiting on that VACUUM FULL.
>
> I also imagine this is the cause. One way to test would be to do:
> BEGIN; LOCK TABLE <name of table>; and see if the connections pile up
> in a similar way to when the VACUUM FULL command is used.
>
> David
>

Thanks folks. David really straight-forward way to test. I validated this,
when I lock the two tables involved in the benchmark the connections are
constantly growing until they reach the `max_connections`