Re: Re: Postgres Parameters

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 <fabrice636861@gmail.com> 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 <sam.stearns@dat.com> 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