Re: Troubleshooting a brief spike in active sessions

Nikolay Samokhvalov <nik@postgres.ai>

From: Nikolay Samokhvalov <nik@postgres.ai>
To: "Dirschel, Steve-CW" <Steve.Dirschel@bestbuy.com>
Cc: "pgsql-performance@lists.postgresql.org" <pgsql-performance@lists.postgresql.org>
Date: 2026-01-09T22:29:20Z
Lists: pgsql-performance
BTW, what are you logging settings for slow queries?
(log_min_duration_statement, auto_explain.log_min_duration)

On Fri, Jan 9, 2026 at 2:27 PM Nikolay Samokhvalov <nik@postgres.ai> wrote:

> On Fri, Jan 9, 2026 at 1:41 PM Dirschel, Steve-CW <
> Steve.Dirschel@bestbuy.com> wrote:
> >
> > Aurora Postgres version 17.4
> >
> > ...
> >
> > The app sessions will show as wait_event_type and wait_event as null
> which I understand means they are on CPU
> >
> > ...
>
>
> Not necessarily. It also might be an uninstrumented wait event.
>
> Do the spikes of "CPU" AAS (I prefer to call them "CPU*") correspond well
> to the spikes of high usage?
>
> If you have N active sessions marked as CPU in ASH, does it match to the
> CPU load of similar scale?
>
> If the VM has much less than 400 vCPUs and you see overall CPU load far
> from 100%, then we should suspect some missing wait event.
>
> Nik
>