Re: postgresql transaction id monitoring with nagios

On 5/2/06, Bruno Wolff III <bruno(at)wolff(dot)to> wrote:
> On Tue, May 02, 2006 at 12:06:30 -0700,
> Tony Wasson <ajwasson(at)gmail(dot)com> wrote:
> >
> > Ah thanks, it's a bug in my understanding of the thresholds.
> >
> > "With the standard freezing policy, the age column will start at one
> > billion for a freshly-vacuumed database."
> >
> > So essentially, 1B is normal, 2B is the max. The logic is now..
> >
> > The script detects a wrap at 2 billion. It starts warning once one or
> > more databases show an age over 1.5 billion transactions. It reports
> > critical at 1.75B transactions.
> >
> > If anyone else understands differently, hit me with a clue bat.
>
> Isn't this obsolete now anyway? I am pretty sure 8.1 has safeguards against
> wrap around.

My motivation was primarily to monitor some existing PostgreSQL 8.0
servers. I'm not convinced it is "safe" to stop worrying about
transaction ids even on an 8.1 box.

It is comforting that 8.1 does safeguard against wraparound in at
least 2 ways. First, it emits a warnings during the last 10 million
transactions. If you manage to ignore all those, posgresql will shut
down before a wraparound. I think PostgreSQL does everything correctly
there, but I suspect someone will run into the shut down daemon
problem.