Date: Wed, 19 Mar 2025 05:50:28 +0000
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Xuneng Zhou <xunengzhou@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Andres Freund <andres@anarazel.de>
Subject: Re: Fwd: [BUG]: the walsender does not update its IO statistics
 until it exits
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Hi,

On Wed, Mar 19, 2025 at 02:26:47PM +0900, Michael Paquier wrote:
> On Wed, Mar 19, 2025 at 09:53:16AM +0800, Xuneng Zhou wrote:
> > I think these two conditions are good too. In a busy system, they are met
> > frequently, so the flush routine will be executed at least once every
> > second. Conversely, when WAL generation is low, there's simply less data to
> > record, and the flush frequency naturally decreases.
> 
> Hmm, yeah, perhaps this is acceptable.  The changes in pgstat.c seem
> inconsistent, though, only moving the min interval while the max and
> idle times stay around.

That's right. OTOH that sounds weird to move the others 2: that would create 
wider visibility for them without real needs. That's not a big issue,
but could impact extensions or friends that would start using those should we
change their values in the future. 

Another option could be to create a dedicated one in walsender.c but I'm not
sure I like it more.

> This also make me wonder if we should work towards extending
> pgstat_report_stat(), so as we save in GetCurrentTimestamp() while
> making the internals still local to pgstat.c.  Or perhaps not in the
> scope of a backpatchable design.

I see. I think I'd vote for making the same changes on HEAD and the STABLE branches
as a first step. And then think about a new "design" that could be part of the
ideas suggested by Andres in [1]. Thoughts?

Regards,

[1]: https://www.postgresql.org/message-id/erpzwxoptqhuptdrtehqydzjapvroumkhh7lc6poclbhe7jk7l%40l3yfsq5q4pw7

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com