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help / color / mirror / Atom feedFrom: [email protected] <[email protected]>
To: Sam Stearns <[email protected]>
To: Fabrice Chapuis <[email protected]>
To: Laurenz Albe <[email protected]>
To: Ron Johnson <[email protected]>
Cc: Pgsql-admin <[email protected]>
Cc: Henry Ashu <[email protected]>
Subject: Re: Re: Postgres Parameters
Date: Wed, 12 Nov 2025 10:26:45 +0800
Message-ID: <[email protected]> (raw)
References: <CAN6TVj=QOuZDGdZegGN1ac0GPM7DgoYMBAWOJHLM68KprMAW1Q@mail.gmail.com>
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<CAN6TVjmO7Tqd1RKqcjrD2LFFcrmSThx+CNuhjWKNHSGO6HVNEQ@mail.gmail.com>
I found that PostgreSQL 15.3 doesn't support the pg_stat_checkpointer view. We can use pg_stat_bgwriter instead. The SQL is as follows:
SELECT
checkpoints_timed AS num_timed, -- Checkpoints triggered by timeout
checkpoints_req AS num_requested, -- Checkpoints triggered by requests (like when WAL space is tight)
round(
(checkpoints_req::numeric / NULLIF(checkpoints_timed + checkpoints_req, 0)) * 100,
2
) AS requested_pct -- % of checkpoints that were request-triggered
FROM pg_stat_bgwriter;
From: Sam Stearns
Date: 2025-11-11 23:24
To: Fabrice Chapuis; Laurenz Albe; Ron Johnson
CC: Pgsql-admin; Henry Ashu
Subject: Re: Postgres Parameters
Awesome stuff. Thank you, everyone!
Sam
On Tue, Nov 11, 2025 at 3:19 AM Fabrice Chapuis <[email protected]> wrote:
Hi, You could also use this query, if the ratio is low, that means there is no pressure on wal size and you can keep the max_wal_size value as it is. SELECT num_timed, num_requested, round((num_requested: : numeric / NULLIF(num_timed + num_requested,
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Hi,
You could also use this query, if the ratio is low, that means there is no pressure on wal size and you can keep the max_wal_size value as it is.
SELECT
num_timed,
num_requested,
round((num_requested::numeric / NULLIF(num_timed + num_requested, 0)) * 100, 2)
AS requested_pct
FROM pg_stat_checkpointer;
+-----------+---------------+---------------+
| num_timed | num_requested | requested_pct |
+-----------+---------------+---------------+
| 3502 | 146 | 4.00 |
+-----------+---------------+---------------+
(1 row)
Regards,
Fabrice
On Tue, Nov 11, 2025 at 12:28 AM Sam Stearns <[email protected]> wrote:
Howdy,
Could someone advise on how to determine the correct settings for the following, please?:
checkpoint_timeout
max_wal_size
Thank you,
Sam
--
Samuel Stearns
Team Lead - Database
c: 971 762 6879 | o: 971 762 6879 | DAT.com
--
Samuel Stearns
Team Lead - Database
c: 971 762 6879 | o: 971 762 6879 | DAT.com
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