From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
To: pgsql-admin@lists.postgresql.org
Subject: Re: pg_stat_database.xact_commit + pg_stat_database.xact_rollback as a reliable metric for xid consumption ?
Date: Mon, 1 Jun 2020 21:13:02 +0300
Message-ID: <3d0096c7-f79f-5100-fe16-55677ce67006@matrix.gatewaynet.com> (raw)
In-Reply-To: <CAODZiv4jb12wTPTnQqv5E291ZSGSAw7VkmKH1Ajeqw3jTON7Pw@mail.gmail.com>
References: <51fa222b-374e-39da-eb8c-66d667426bae@matrix.gatewaynet.com>
<CAOBaU_Zc5o=pKopyh=U02xw_FPN_ZWBhqe=-hSTPC-n7JF=X2g@mail.gmail.com>
<36dd7ae2-7c6f-86af-430b-dd9a0f7774b3@matrix.gatewaynet.com>
<CAOBaU_b3BG2jicgv7Woyo8vT1V3dnw4xPvMR=AuZ6hMWYuPjKQ@mail.gmail.com>
<eaded5fd-379e-1bd8-ebc6-dc85d72db4d1@matrix.gatewaynet.com>
<CAODZiv4jb12wTPTnQqv5E291ZSGSAw7VkmKH1Ajeqw3jTON7Pw@mail.gmail.com>
On 1/6/20 5:52 μ.μ., Keith Fiske wrote:
>
>
> On Mon, Jun 1, 2020 at 8:41 AM Achilleas Mantzios
> <achill@matrix.gatewaynet.com <mailto:achill@matrix.gatewaynet.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@matrix.gatewaynet.com
> <mailto:achill@matrix.gatewaynet.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@matrix.gatewaynet.com
> <mailto:achill@matrix.gatewaynet.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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-admin@postgresql.org
Cc: achill@matrix.gatewaynet.com, pgsql-admin@lists.postgresql.org
Subject: Re: pg_stat_database.xact_commit + pg_stat_database.xact_rollback as a reliable metric for xid consumption ?
In-Reply-To: <3d0096c7-f79f-5100-fe16-55677ce67006@matrix.gatewaynet.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox