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

Sami Imseih <samimseih@gmail.com>

From: Sami Imseih <samimseih@gmail.com>

To: Michael Paquier <michael@paquier.xyz>

Cc: Chao Li <li.evan.chao@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-12-08T19:09:14Z

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 →

Fix const correctness in pgstat data serialization callbacks
- 167cb26718e3 19 (unreleased) landed
test_custom_stats: Add tests with read/write of auxiliary data
- 481783e69f14 19 (unreleased) landed
Allow cumulative statistics to read/write auxiliary data from/to disk
- 4ba012a8ed9c 19 (unreleased) landed
test_custom_stats: Test module for custom cumulative statistics
- 31280d96a648 19 (unreleased) landed
injection_points: Remove portions related to custom pgstats
- d52c24b0f808 19 (unreleased) landed
Rename routines for write/read of pgstats file
- ed823da12891 19 (unreleased) landed

Attachments

v5-0001-Allow-cumulative-statistics-to-serialize-auxiliar.patch (application/octet-stream) patch v5-0001

> Yes, thanks.  Structurally, this is better and more flexible than what
> we had originally, and I have noticed that you have copied the
> original files while adding more comments and renaming a bit things:
> the structure of the functions was exactly the same.  Anyway, I have
> worked on that for a good portion of the day, splitting the module
> drop and the new module into two commits, and applied the result after
> tweaking quite a few things in terms of names and comments (no
> pgstat_*, a bit more "Var" and "Fixed", etc.), applying a much more
> consistent set of names across the board for the functions and the
> structures.  This cleanup part is moved out of the way now, so that
> you ease the introduction of the next pieces you are proposing.

Thanks for getting these committed!

I rebased the custom callbacks patch in v5.

One very minor thing from the earlier commits that I corrected here is
the test for entry 2 after a clean restart.

-is($result, "entry1|2", "variable-sized stats persist after clean restart");
+is($result, "entry1|2|Test entry 1", "variable-sized stats persist
after clean restart");
+
+$result = $node->safe_psql('postgres', q(select * from
test_custom_stats_var_report('entry2')));
+is($result, "entry2|3|Test entry 2", "variable-sized stats persist
after clean restart");
+

--
Sami Imseih
Amazon Web Services (AWS)