Re: add recovery, backup, archive, streaming etc. activity messages to server logs along with ps display

On Thu, Dec 9, 2021 at 9:28 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>
> On 2021-Dec-09, Bharath Rupireddy wrote:
>
> > On Thu, Dec 9, 2021 at 6:00 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> > >
> > > On 2021-Dec-09, Bharath Rupireddy wrote:
> > >
> > > > I just want to call this out: an insertion of 10 million rows in the
> > > > primary generates a bunch of messages in the standby [1] within 40 sec
> > > > (size of the standby server log grows by 5K).
> > >
> > > Hmm, that does sound excessive to me in terms of log bloat increase.
> > > Remember the discussion about turning log_checkpoints on by default?
> >
> > The amount of LOG messages generated when the log_checkpoints GUC is
> > set to on, are quite less, hardly 4 messages per-checkpoint (5min). I
> > think enabling log_checkpoints is still acceptable as most of the
> > hackers agreed in another thread [1] that the advantages with it are
> > more and it doesn't seem to be bloating the server logs (in a day at
> > max 1152 messages).
>
> My point is that it was argued, in that thread, that setting
> log_checkpoints to on by default would cause too much additional log
> volume. That argument was shot down, but in this thread we're arguing
> that we want five kilobytes of messages in forty seconds. That sounds
> much less acceptable to me, so making it default behavior or
> unconditional behavior is not going to fly very high.
>
> > I'm not sure if it is worth having a GUC log_recovery if enabled the
> > recovery messages can be emitted at LOG level otherwise DEBUG1 level.
>
> Maybe some tunable like
> log_wal_traffic = { none, medium, high }
> where "none" is current behavior of no noise, "medium" gets (say) once
> every 256 segments (e.g., when going from XFF to (X+1)00), "high" gets
> you one message per segment.

Yeah, that can be an option.

Another idea could be to use the infrastructure laid out by the commit
9ce346e [1]. With ereport_startup_progress, we can emit the LOGs(of
current recovering WAL file) for every log_startup_progress_interval
seconds/milliseconds.

One problem is that ereport_startup_progress doesn't work on
StandbyMode, maybe we can remove this restriction unless we have a
major reason for not allowing it on the standby.
/* Prepare to report progress of the redo phase. */
if (!StandbyMode)
begin_startup_progress_phase();

Thoughts?

[1]
commit 9ce346eabf350a130bba46be3f8c50ba28506969
Author: Robert Haas <rhaas(at)postgresql(dot)org>
Date: Mon Oct 25 11:51:57 2021 -0400

Report progress of startup operations that take a long time.

Discussion:
https://postgr.es/m/CA+TgmoaHQrgDFOBwgY16XCoMtXxsrVGFB2jNCvb7-ubuEe1MGg@mail.gmail.com
Discussion:
https://postgr.es/m/CAMm1aWaHF7VE69572_OLQ+MgpT5RUiUDgF1x5RrtkJBLdpRj3Q@mail.gmail.com

Regards,
Bharath Rupireddy.