On 1/6/20 5:52 μ.μ., Keith Fiske wrote:
>
>
> On Mon, Jun 1, 2020 at 8:41 AM Achilleas Mantzios
> <achill(at)matrix(dot)gatewaynet(dot)com <mailto:achill(at)matrix(dot)gatewaynet(dot)com>>
> wrote:
>
> Hello Julien
> On 1/6/20 2:03 μ.μ., Julien Rouhaud wrote:
> > On Mon, Jun 1, 2020 at 12:48 PM Achilleas Mantzios
> > <achill(at)matrix(dot)gatewaynet(dot)com
> <mailto:achill(at)matrix(dot)gatewaynet(dot)com>> wrote:
> >> On 1/6/20 1:36 μ.μ., Julien Rouhaud wrote:
> >>> On Mon, Jun 1, 2020 at 12:02 PM Achilleas Mantzios
> >>> <achill(at)matrix(dot)gatewaynet(dot)com
> <mailto:achill(at)matrix(dot)gatewaynet(dot)com>> wrote:
> >>> Because read only transaction usually don't consume an xid.
> So yes
> >>> pg_stat_database gives a more reasonable approximation of the real
> >>> number of transactions happening on the server.
> >> Thank you, so what would be the official way to monitor txid
> consumption (from a MVCC / Freezing admin POV)?
> > I'm not sure what you're really looking for.
> I've been as explicit as it gets. When ppl talk about vacuum
> freeze what they have in mind is xmin's and xmax's and the rate
> that xids grow and consume the 2^31 address space, so I find it
> strange
> that such a basic metric is not included in the core statistics
> collector.
> That's all.
> >
>
>
> --
> Achilleas Mantzios
> IT DEV Lead
> IT DEPT
> Dynacom Tankers Mgmt
>
>
>
>
> I've done a writeup on effectively monitoring for xid
> exhaustion/wraparound.
>
> https://info.crunchydata.com/blog/managing-transaction-id-wraparound-in-postgresql
>
Thank you, seems like a nice write-up, I'll check this out.
> It is relatively simple to get the current xid state applying the
> age() function to the pg_database catalog:
>
> SELECT datname, age(datfrozenxid),
> current_setting('autovacuum_freeze_max_age') FROM pg_database ORDER BY
> 2 DESC;
>
> But the query in the linked blog post provides things in a more
> user-friendly manner for monitoring purposes as simple percentages
>
> --
> Keith Fiske
> Senior Database Engineer
> Crunchy Data - http://crunchydata.com