Re: CHECKPOINT unlogged data

Nathan Bossart <nathandbossart@gmail.com>

From: Nathan Bossart <nathandbossart@gmail.com>

To: Andres Freund <andres@anarazel.de>

Cc: Christoph Berg <myon@debian.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-05-30T17:07:48Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Add FLUSH_UNLOGGED option to CHECKPOINT command.
- 8d33fbacbac9 19 (unreleased) landed
Add MODE option to CHECKPOINT command.
- 2f698d7f4b7b 19 (unreleased) landed
Add option list to CHECKPOINT command.
- a4f126516e68 19 (unreleased) landed
Rename CHECKPOINT_FLUSH_ALL to CHECKPOINT_FLUSH_UNLOGGED.
- cd8324cc89a9 19 (unreleased) landed
Rename CHECKPOINT_IMMEDIATE to CHECKPOINT_FAST.
- bb938e2c3c7a 19 (unreleased) landed

On Fri, May 30, 2025 at 12:39:02PM -0400, Andres Freund wrote:
> On 2025-05-30 18:17:45 +0200, Christoph Berg wrote:
>> A customer reported to use CHECKPOINT before shutdowns to make the
>> shutdowns themselves faster and asked if it was possible to make
>> CHECKPOINT optionally also write out unlogged table data for that
>> purpose. I think the idea makes sense, so there's the patch.
> 
> I've seen the need for this quite a few times, fwiw. So +1 to the idea.

This patch also adds an IMMEDIATE option, which I proposed some time ago
[0].  I ended up withdrawing it due to general skepticism about its
usefulness.  FWIW I have no concerns about adding a few retail options to
CHECKPOINT, but others might balk at options without solid use-cases.  The
unlogged table one seems reasonable enough.

[0] https://postgr.es/m/17A03557-CF5C-4D4B-B719-A1D98DD75E75%40amazon.com

-- 
nathan