public inbox for [email protected]
help / color / mirror / Atom feedFrom: Michael Paquier <[email protected]>
To: Sami Imseih <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: [Proposal] Adding callback support for custom statistics kinds
Date: Mon, 24 Nov 2025 09:10:29 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAA5RZ0tH6ih3anQ=Lcwttm+8BURJ8VkBoy_9V8Ty73ZA1r384Q@mail.gmail.com>
References: <CAA5RZ0s9SDOu+Z6veoJCHWk+kDeTktAtC-KY9fQ9Z6BJdDUirQ@mail.gmail.com>
<[email protected]>
<CAA5RZ0ux07=E97mJ3JCy2jhs349NKzj7SPJNbDWZ11m9BDkTQQ@mail.gmail.com>
<CAA5RZ0tnopAS4MCcoxXdJShYoGxYZgsoDXCjcie0Q-2TBPuJwA@mail.gmail.com>
<[email protected]>
<CAA5RZ0skT-uWwgrCg3Hj3AQaBbQdN0h72scD9GBLxH1nEKSNwQ@mail.gmail.com>
<CAA5RZ0tH6ih3anQ=Lcwttm+8BURJ8VkBoy_9V8Ty73ZA1r384Q@mail.gmail.com>
On Wed, Nov 19, 2025 at 08:10:43PM -0600, Sami Imseih wrote:
> It just occurred to me that the documentation [0] should be
> updated to describe the callbacks. I will do that in the next
> revision.
>
> [0] https://www.postgresql.org/docs/current/xfunc-c.html#XFUNC-ADDIN-CUSTOM-CUMULATIVE-STATISTICS
Hmm. Based on what I can read from the patch, you are still enforcing
file name patterns in the backend, as of:
+ extra->statfiles[i] = psprintf("%s/pgstat.%d.%d.stat",
+ PGSTAT_STAT_PERMANENT_DIRECTORY, kind, i);
My take (also mentioned upthread) is that this design should go the
other way around, where modules have the possibility to define their
own file names, and some of them could be generated on-the-fly when
writing the files, for example for a per-file database split, or the
object ID itself.
The important part for variable-numbered stats is that the keys of the
entries have to be in the main pgstats file. Then, the extra data is
loaded back based on the data in the entry key, based on a file name
that only a custom stats kind knows about (fd and file name). It
means that the custom stats kind needs to track the files it has to
clean up by itself in this scheme. We could pass back to the startup
process some fds that it cleans up, but it feels simpler here to let
the custom code do what they want, instead, rather than having an
array that tracks the file names and/or their fds.
--
Michael
Attachments:
[application/pgp-signature] signature.asc (833B, ../[email protected]/2-signature.asc)
download
view thread (47+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected], [email protected]
Subject: Re: [Proposal] Adding callback support for custom statistics kinds
In-Reply-To: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox