Re: Function to track shmem reinit time

FWIW, I don't object for adding the feature like this (in other words
+1), since I see the advantages Alex mentioned is valid. (Even though
most of our customers notices server restart by client
disconnections..)

At Wed, 8 Apr 2020 11:49:11 -0400, David Steele <david(at)pgmasters(dot)net> wrote in
> On 2/24/20 10:57 PM, Robert Haas wrote:
> > On Sat, Feb 22, 2020 at 10:31 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> I'm still going to object to it, on the grounds that
> >>
> >> (1) it's exposing an implementation detail that clients should not be
> >> concerned with, and that we might change in future. The name isn't
> >> even well chosen --- if the argument is that it's useful to monitor
> >> server uptime, why isn't the name "pg_server_uptime"?
> >>
> >> (2) if your server is crashing often enough that postmaster start
> >> time isn't an adequate substitute, you have way worse problems than
> >> whether you can measure it. I'd rather see us put effort into
> >> fixing whatever the underlying problem is.
> > I don't accept the first argument, because I think the chances that
> > we'll change our basic approach to this problem are indistinguishable
> > from zero. A few years back, you criticized some idea of mine as
> > tantamount to rm -rf src/backend/optimizer, which you were not ready
> > to endorse. That proposal was surely vastly less ambitious than some
> > proposal which would remove the idea of shared memory reinitialization
> > after an unsafe backend exit.

I'm not sure the name is good, mainly for the reason of
user-friendliness. Alexander's proposal "pg_server_up_since()"
returning absolute time makes sense to me.

> > I don't accept the second argument either, because it's a false
> > dichotomy. Adding this function won't reduce the amount of energy that
> > gets spent fixing crashes. There are always more crashes.
> > I realize that several other people voted against this proposal so I
> > don't think it's OK to commit a patch in this area unless some more
> > positive votes turn up, but I'm still +1 on the idea. Granted, we
> > don't want an infinite amount of clutter in the system catalogs, but I
> > have a hard time believing that this proposed function would get any
> > less use than the hyperbolic trig functions.

I'm on Robert and Alexander side about this. I don't think
introducing this necessarily means we are obliged to accept all
requests for "last $anything" for other events, like introducing the
hyperbolic functions doesn't mean to accept all new functions alike,
maybe.

> Marking this Returned with Feedback again since we are still at an
> impasse.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center