Horton

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

Chao Li <li.evan.chao@gmail.com>

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From: Chao Li <li.evan.chao@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Sami Imseih <samimseih@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-09T05:23:56Z
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 Dec 9, 2025, at 12:45, Michael Paquier <michael@paquier.xyz> wrote:
> 
> It seems to me that you are missing nothing here, and that Chao has
> missed the fact that the end of pgstat_read_statsfile() does a "goto
> done", meaning that we would take a round of

No, I didn’t miss that part. But in the “done” clause:

```
done:
/* First, cleanup the main stats file, PGSTAT_STAT_PERMANENT_FILENAME */
FreeFile(fpin);

elog(DEBUG2, "removing permanent stats file \"%s\"", statfile);
unlink(statfile);

/* Let each stats kind run its cleanup callback, if it provides one */
for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
{
const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);

if (kind_info && kind_info->end_extra_stats)
kind_info->end_extra_stats(STATS_READ);
}
```

end_extra_stats(STATS_READ) has no failure indication.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/