Re: monitoring usage count distribution

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org, schneider@ardentperf.com
Date: 2023-04-07T18:29:31Z
Lists: pgsql-hackers
Nathan Bossart <nathandbossart@gmail.com> writes:
> On Thu, Apr 06, 2023 at 01:32:35PM -0400, Tom Lane wrote:
>> There seems to be enough support for the existing summary function
>> definition to leave it as-is; Andres likes it for one, and I'm not
>> excited about trying to persuade him he's wrong.  But a second
>> slightly-less-aggregated summary function is clearly useful as well.
>> So I'm now thinking that we do want the patch as-submitted.
>> (Caveat: I've not read the patch, just the description.)

> In case we want to do both, here's a 0002 that changes usagecount_avg to an
> array of usage counts.

I'm not sure if there is consensus for 0002, but I reviewed and pushed
0001.  I made one non-cosmetic change: it no longer skips invalid
buffers.  Otherwise, the row for usage count 0 would be pretty useless.
Also it seemed to me that sum(buffers) ought to agree with the
shared_buffers setting.

			regards, tom lane



Commits

  1. Add pg_buffercache_usage_counts() to contrib/pg_buffercache.