Horton

Re: [Proposal] Adding callback support for custom statistics kinds

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Sami Imseih <samimseih@gmail.com>
Cc: Chao Li <li.evan.chao@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-04T23:14:58Z
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 →

  1. Fix const correctness in pgstat data serialization callbacks

  2. test_custom_stats: Add tests with read/write of auxiliary data

  3. Allow cumulative statistics to read/write auxiliary data from/to disk

  4. test_custom_stats: Test module for custom cumulative statistics

  5. injection_points: Remove portions related to custom pgstats

  6. Rename routines for write/read of pgstats file

On Thu, Dec 04, 2025 at 05:00:10PM -0600, Sami Imseih wrote:
> Thanks for the input! Yes, this is a trade-off between putting
> responsibility on the
> extension vs core. The initial thought I had was exactly like yours, but it will
> be easier to get something pushed if we make the core changes as minimal as
> possible. If there are enough complaints in the future, this can be revisited.
> Particularly if there is a common patterns for file cleanup, this
> could be turned
> into a core utility.

Another way to shape it would be to have an in-core routine that
provides a default logic for the actions to take depending on the
write, read or discard state, with the state and a FILE* as arguments.
The main pgstats file would call that, modules may decide to use it.

> However, as discussed off-list, I do think moving the custom kind tests from
> injection points to the new test module is a prerequisite. I rather
> not have us push a new test module that is doing duplicate work as the injection
> stats tests.
> I worked on this refactoring today and plan to have a patch ready for review
> by tomorrow.

Cool, thanks!
--
Michael