Re: The Curious Case of the Table-Locking UPDATE Query

Attach the files.

Best regards,

On Tue, Jul 6, 2021 at 6:24 AM hubert depesz lubaczewski <depesz(at)depesz(dot)com>
wrote:

> On Mon, Jul 05, 2021 at 08:22:39PM -0300, Emiliano Saenz wrote:
> > We have a huge POSTGRES 9.4 database in the production environment
> (several
> > tables have more than 100.000.00 registers). Last two months we have had
> > problems with CPU utilization. Debugging the locks (on pg_locks) we
> notice
> > that sometimes simple UPDATE (by primary key) operation takes out
> > ACCESS_EXCLUSIVE_LOCK mode over these huge tables so POSTGRES DB
> collapses
> > and it generates excessive CPU consumption. My question is, How is it
> > possible that UPDATE operation takes out ACCESS_EXCLUSIVE_LOCK mode?
> > More information, this system never manifests this behavior before and we
> > don't make software changes on last 2 years
>
>
> To be able to help we will need pg_stat_activity data for the for
> backend that has this lock, and pg_locks information for it too.
>
> And, please, send text, and not screenshot.
>
> Best regards,
>
> depesz
>
>